migrating sybase apis to sql server

8/12/2019 Migrating Sybase aPis to sQl Server

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Guide to Migrating Sybase Application Interfaces to SQL

Server 2008

SQL Server Technical Article

Writers:Yuri Rusakov (DB Best Technologies), Alexander Pavlov (DB Best Technologies), Yuri

Kovtun (DB Best Technologies)

Technical Reviewer:Dmitry Balin (DB Best Technologies)

Published:

Applies to:SQL Server 2008

Summary:This white paper describes methods of migrating applications with Sybase interfacesto SQL Server. We cover both Open Standard APIs (ODBC, JDBC, OLE DB, ADO.Net) and

proprietary APIs (CT-Library, DB-Library).

Created by: DB Best Technologies LLC

P.O. Box 7461, Bellevue, WA 98008

Tel.: (408) 202-4567

E-mail: [email protected]

Web: www.dbbest.com
mailto:[email protected]://d/WP-JOEL/OUT/www.dbbest.comhttp://d/WP-JOEL/OUT/www.dbbest.comhttp://d/WP-JOEL/OUT/www.dbbest.commailto:[email protected]


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CopyrightThis is a preliminary document and may be changed substantially prior to final commercial

release of the software described herein.

The information contained in this document represents the current view of Microsoft Corporation

on the issues discussed as of the date of publication. Because Microsoft must respond tochanging market conditions, it should not be interpreted to be a commitment on the part of

Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the

date of publication.

This White Paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES,

EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT.

Complying with all applicable copyright laws is the responsibility of the user. Without limiting the

rights under copyright, no part of this document may be reproduced, stored in or introduced into

a retrieval system, or transmitted in any form or by any means (electronic, mechanical,

photocopying, recording, or otherwise), or for any purpose, without the express writtenpermission of Microsoft Corporation.

Microsoft may have patents, patent applications, trademarks, copyrights, or other intellectual

property rights covering subject matter in this document. Except as expressly provided in any

written license agreement from Microsoft, the furnishing of this document does not give you any

license to these patents, trademarks, copyrights, or other intellectual property.

Unless otherwise noted, the example companies, organizations, products, domain names, e-

mail addresses, logos, people, places and events depicted herein are fictitious, and no

association with any real company, organization, product, domain name, email address, logo,

person, place or event is intended or should be inferred.

2010 Microsoft Corporation. All rights reserved.

Microsoft and SQL Server are registered trademarks of Microsoft Corporation in the United

States and other countries.

The names of actual companies and products mentioned herein may be the trademarks of their

respective owners.


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Contents

Copyright ................................................................................................................................... 2

Introduction ................................................................................................................................ 4

Conversion of Open Standard Application Interfaces ................................................................. 5

Overview ................................................................................................................................ 5

JDBC ...................................................................................................................................... 5

ODBC ..................................................................................................................................... 5

OLE DB .................................................................................................................................. 6

ADO.NET ............................................................................................................................... 8

Driver versions ....................................................................................................................... 9

Open Client Libraries to ODBC Migration ..................................................................................11

Overview ...............................................................................................................................11

Main Migration Steps .............................................................................................................11

CT-Library Schema migration ................................................................................................12

Header files mapping .........................................................................................................12

Routine mapping ................................................................................................................12

Type and structure mapping...............................................................................................17

DB-Library Schema migration ................................................................................................20

Overview ............................................................................................................................20

Header files mapping .........................................................................................................20

Routine mapping ................................................................................................................20

Type and structure mapping...............................................................................................25

Other Types of Migration ...........................................................................................................27

Using FreeTDS tool to migrate CT Library and DB Library applications to SQL Server .........27

Migration of Open Client Embedded SQL ..............................................................................27

Migration of ASE Job Scheduler objects ................................................................................28

Conversion of Transact-SQL statements which are embedded in applications ......................28

Conclusion ................................................................................................................................30

About DB Best Technologies .................................................................................................30


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Introduction

DB Best Technologies, Inc. created several white papers which cover migration of databases,

such as Oracle or Sybase ASE, to SQL Server 2008. However, in most of the cases there is

also a necessity to change database access code in an application connecting to the migrateddatabase.

The task is easiest when the application uses a database interface designed to serve many

database servers. In this white paper we discuss Open Database Connectivity (ODBC), Java

Database Connectivity (JDBC), Object Linking and Embedding Database (OLE DB) and ActiveX

Data Objects for .NET (ADO.NET). Migration of such interfaces can be as simple as changing

the database driver and/or connection strings.

More complicated are the cases when we use proprietary interfaces of one database vendor,

which do not provide connectivity to SQL Server 2008. Examples are Sybase ASE CT-Library

and DB-Library. In this paper we describe how to change the application code to use SQLServer compatible ODBC interface.


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Conversion of Open Standard Application Interfaces

Overview

In this section we discuss methods of redirecting multi-database interfaces of Sybase Adaptive

Server Enterprise (ASE) applications to SQL Server 2008.

Note that the application code may contain pieces of SQL strings, which are sent to the

database and which may not be compatible with SQL Server after the interface was redirected.

In such cases, we should convert the embedded SQL according to the rules of SQL conversion.

JDBC

To convert a JDBC application, we need to change name of loaded JDBC driver class and

modify its URL accordingly.

Examples:

JDBC connection to Sybase ASE:

Class.forName(com.sybase.jdbc.SybDrive);

String url = "jdbc:sybase:Tds:sybase_server_name:5000/test_base;

Connection dbc = DriverManager.getConnection(url, login, password);

See below the changes necessary to make this code connect to SQL Server. The class

name of SQL Server driver should be specified as a parameter of Class.forName() method,

and getConnection method of the loaded class should follow the URL syntax for SQL

Server.

Class.forName(com.microsoft.sqlserver.jdbc.SQLServerDriver);

String url = jdbc:sqlserver://sql_server_name:1433;

Connection dbc = DriverManager.getConnection(url, login, password);

ODBC

ODBC is a universal interface, which means we can change the servers just by specifying

another Data Source Name. See below a typical example of switching the database in ODBC

connect code.


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ODBC connection to Sybase:

SQLRETURN retcode;

SQLHENV env;

SQLHDBC dbc;retcode = SQLAllocHandle( SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env );retcode = SQLSetEnvAttr( env, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3,

0);retcode = SQLAllocHandle( SQL_HANDLE_DBC, env, &dbc );retcode = SQLConnect(dbc,

(SQLCHAR*) "sybase_DataSource_name", SQL_NTS,(SQLCHAR*) "sybase_login", SQL_NTS,(SQLCHAR*) "sybase_password", SQL_NTS);

ODBC connection to SQL Server:

SQLRETURN retcode;SQLHENV env;

SQLHDBC dbc;

retcode = SQLAllocHandle( SQL_HANDLE_ENV, SQL_NULL_HANDLE, &env );retcode = SQLSetEnvAttr( env, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3,

0);retcode = SQLAllocHandle( SQL_HANDLE_DBC, env, &dbc );retcode = SQLConnect(dbc,

(SQLCHAR*) "mssql_DataSource_name", SQL_NTS,(SQLCHAR*) "mssql_login", SQL_NTS,(SQLCHAR*) "mssql_password", SQL_NTS);

OLE DB

To establish a connection with a data source we need to create an instance of OLE DB

provider, which exposes interfaces of the data source, and then to perform initialization of this

instance. To do that, we should use function CoCreateInstance with OLE DB provider class ID

as the first parameter. Next, we initialize the data source using array of structures DBPROP. In

the simplest case, we need to specify four properties: prompt level, DSN name, user name and

password.

The difference between OLE DB connections for different databases is in OLE DB providerobject and object initialization parameters.

Connecting to Sybase ASE with OLE DB:

#include "msdasql.h"


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IDBInitialize* pIDBInitialize = NULL;HRESULT hr;hr = CoCreateInstance(CLSID_MSDASQL,

NULL,CLSCTX_INPROC_SERVER,

IID_IDBInitialize,(void**)&pIDBInitialize);

InitProperties[0].dwPropertyID = DBPROP_INIT_PROMPT;InitProperties[0].vValue.vt = VT_I2;InitProperties[0].vValue.iVal = DBPROMPT_NOPROMPT;InitProperties[1].dwPropertyID = DBPROP_INIT_DATASOURCE;InitProperties[1].vValue.vt = VT_BSTR;InitProperties[1].vValue.bstrVal =SysAllocString(OLESTR("sybase_DataSource_name"));InitProperties[2].dwPropertyID = DBPROP_AUTH_USERID;InitProperties[2].vValue.vt = VT_BSTR;

InitProperties[2].vValue.bstrVal = SysAllocString(OLESTR("sybase_login"));InitProperties[3].dwPropertyID = DBPROP_AUTH_PASSWORD;InitProperties[3].vValue.vt = VT_BSTR;InitProperties[3].vValue.bstrVal = SysAllocString(OLESTR("sybase_password"));

Connecting to SQL Server using OLE DB:

#include "msdasql.h"

IDBInitialize* pIDBInitialize = NULL;HRESULT hr;hr = CoCreateInstance(CLSID_MSDASQL,

NULL,CLSCTX_INPROC_SERVER,IID_IDBInitialize,(void**)&pIDBInitialize);

InitProperties[0].dwPropertyID = DBPROP_INIT_PROMPT;InitProperties[0].vValue.vt = VT_I2;InitProperties[0].vValue.iVal = DBPROMPT_NOPROMPT;InitProperties[1].dwPropertyID = DBPROP_INIT_DATASOURCE;

InitProperties[1].vValue.vt = VT_BSTR;InitProperties[1].vValue.bstrVal =SysAllocString(OLESTR("mssql_DataSource_name"));InitProperties[2].dwPropertyID = DBPROP_AUTH_USERID;InitProperties[2].vValue.vt = VT_BSTR;InitProperties[2].vValue.bstrVal =SysAllocString(OLESTR("mssql_login"));InitProperties[3].dwPropertyID = DBPROP_AUTH_PASSWORD;InitProperties[3].vValue.vt = VT_BSTR;


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InitProperties[3].vValue.bstrVal =SysAllocString(OLESTR("mssql_password"));

When using ATL library, we should choose class CDataSource for connection to a database.

Databases differ by parameters of Open() method.

CDataSource dsDSN;HRESULT hr;

// Connecting to Sybase ASE with ATL OLE DB:

hr = dsDSN.Open(_T("MSDASQL"), sybase_DataSource_name,"sybase_login", "sybase_password");

// Connecting to SQL Server with ATL OLE DB:

hr = dsDSN.Open(_T("MSDASQL"), mssql_DataSource_name,"mssql_login", "mssql_password");

ADO.NET

ADO.NET architecture uses data providers to access a database. There are various

implementations of the .NET interfaces for different DBMSes. For example, connections to SQL

Server are handled by special class SqlConnection. Each provider includes its own set of .NET

framework classes in a separate namespace. When performing migration, we should replace

calls to objects of one namespace to the calls of SQL Server provider. The only exception isODBC and OLE DB providers, which by definition are compatible with multiple databases.

When the original provider uses System.Data.Odbc, the Sybase to SQL Server migration may

be as simple as replacement of the connection string.

An example of Sybase connection:

OdbcConnection connection = new OdbcConnection("Driver={SYBASE ASE ODBCDriver};Srvr=myServerAddress;Uid=myUsername;Pwd=myPassword;");

connection.Open();

Equivalent SQL Server connection:

OdbcConnection connection = new OdbcConnection(


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"Driver={SQLServer};Server=(local);Trusted_Connection=Yes;Database=AdventureWorks;");connection.Open();

Similarly, we replace the connection string in case of ADO.NET OLE DB provider.

Sybase OLE DB connection:

OleDbConnection connection = new OleDbConnection("Provider=Sybase.ASEOLEDBProvider;Srvr=myASEserver,5000;Catalog=myDataBase;User Id=myUsername;Password=myPassword;");connection.Open();

SQL Server connection:

OleDbConnection connection = new OleDbConnection("Provider=SQLOLEDB;Server=myServerAddress;Database=myDataBase;Uid=myUsername; Pwd=myPassword;");connection.Open();

When the source code uses Oracle specific provider defined in System.Data.AseClient, we will

need to replace the class names with their counterparts in System.Data.SqlClient.

Sybase connection:

AseConnection connection = newAseConnection (connectionString);connection.Open();

SQL Server connection:

SqlConnection connection = newSqlConnection(connectionString);connection.Open();

Driver versions

We suggest to use this driver in case of JDBC conversion:

http://www.microsoft.com/downloads/details.aspx?familyid=99B21B65-E98F-4A61-B811-

19912601FDC9&displaylang=en

You can take Microsoft SQL Server OLE DB Provider and ODBC driver from Microsoft Data

Access Components (MDAC) :
http://www.microsoft.com/downloads/details.aspx?familyid=99B21B65-E98F-4A61-B811-19912601FDC9&displaylang=enhttp://www.microsoft.com/downloads/details.aspx?familyid=99B21B65-E98F-4A61-B811-19912601FDC9&displaylang=enhttp://www.microsoft.com/downloads/details.aspx?familyid=99B21B65-E98F-4A61-B811-19912601FDC9&displaylang=enhttp://www.microsoft.com/downloads/details.aspx?familyid=99B21B65-E98F-4A61-B811-19912601FDC9&displaylang=enhttp://www.microsoft.com/downloads/details.aspx?familyid=99B21B65-E98F-4A61-B811-19912601FDC9&displaylang=en


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http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6c050fe3-c795-

4b7d-b037-185d0506396c

ADO.NET Data Provider for SQL Server is shipped as a part of MDAC or as a part of .NET

Framework.

.
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6c050fe3-c795-4b7d-b037-185d0506396chttp://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6c050fe3-c795-4b7d-b037-185d0506396chttp://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6c050fe3-c795-4b7d-b037-185d0506396chttp://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6c050fe3-c795-4b7d-b037-185d0506396chttp://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6c050fe3-c795-4b7d-b037-185d0506396c


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Open Client Libraries to ODBC Migration

Overview

Following are the basic, high-level steps for migrating a Sybase Open Client Libraries

interfaces to SQL Server ODBC interface and what you must know about converting

interface routines.

Main Migration Steps

From the point of view of the client program both Sybase Open Client and ODBC represent a

set of the C modules connected to program, containing the description of necessary types

and functions for use of opportunities of the corresponding interface.

Base functionality of libraries is identical and realizes necessary commands for performanceof operations of initialization of the driver, connection to a database server, execute SQL

statement, fetching of results and closings of connection.

Converting a Sybase Open Client Libraries program to its SQL Server ODBC equivalent

generally involves the following steps:

1. Replace Open Client Libraries header file names with the ODBC header file names.

2. Plan the code conversion. Client application code can be split roughly into the

following categories:

Initialization and cleanup code;

Code that opens a connection;

Error and message handlers; Code that sends commands;

Code that processes results;

Finalization code;

3. Perform the conversion:

Replace or remove Open Client Libraries declarations, as appropriate.

Replace Open Client Libraries function calls with their ODBC equivalents, changing

program logic as necessary.


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CT-Library Schema migration

This section explains mappings and differences between CT-Library and ODBC modules,

commands and types.

Header files mapping

The following table displays the list of required header C files for the use CT-Library and

ODBC API.

CT-Library ODBC

#include #include

#include

Routine mapping

The following table displays the commands, used in typical execution steps of CT-Library

and ODBC applications, and their correspondence.

CT-Library ODBC

STEP 1: Set Up The Client-Library

Programming Environment

STEP 1: Connect To The Data Source

cs_ctx_alloc

Allocate a context structure.

cs_configSet any CS-Library properties for the

context.

ct_init

Initialize Client-Library.

SQLAllocHandle(ENV)

Load the Driver Manager and allocate the

environment handle.

Driver Manager allocates a structure in

which to store information about the

environment, and returns the environment

handle.

ct_config

Set Client-Library properties for the

context.

SQLSetEnvAttr

Sets attributes that govern aspects of

environments.

STEP 2: Define Error Handling


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cs_config(CS_MESSAGE_CB)

Install a CS-Library error callback.

Replace with SQLGetDiagFieldand

SQLGetDiagRecfunction calls in the

return code handlers.

SQLGetDiagField

Returns the current value of a field of a

record of the diagnostic data structure(associated with a specified handle) that

contains error, warning, and status

information.

SQLGetDiagRec

Returns the current values of multiple

fields of a diagnostic record that contains

error, warning, and status information.

Unlike SQLGetDiagField, which returns one

diagnostic field per call, SQLGetDiagRec

returns several commonly used fields of a

diagnostic record, including the SQLSTATE,the native error code, and the diagnostic

message text.

ct_callback

Install a client or server message callback.

Ct_callback installs Client-Library callback

routines, which are application

routines that Client-Library calls

automatically when a triggering event of

the appropriate type occurs.

STEP 3: Connect To A Server

ct_con_alloc

Allocate a connection structure.

SQLAllocHandle(DBC)

Allocate a connection handle.



connection and returns the connection

handle.

ct_con_props

Set any properties in the connection

structure.

SQLSetConnectAttr

Sets attributes that govern aspects of

connections.

Some connection attributes must be set

before the application attempts to connect,

others can be set after the connection has

completed.


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ct_connect

Open a connection to a server.

SQLConnector SQLDriverConnector

SQLBrowseConnect

SQLConnect establishes connections to a

driver and a data source.

ct_options

Set any server options for this connection.

STEP 4: Send A Language Command

To The Server

STEP 2: Initialize The Application

ct_cmd_alloc

Allocate a command structure.

SQLAllocHandle(STMT)



statement and calls SQLAllocHandle in the

driver with the SQL_HANDLE_STMT option.

The driver allocates its own structure in


statement and returns the driver

statement handle to the Driver Manager.

The Driver Manager returns the Driver

Manager statement handle.

ct_cmd_props

Set, retrieve, or clear command structure

properties.

SQLSetStmtAttr

Sets attributes related to a statement.

STEP 3: Build And Execute An SQL

Statement

ct_command

Define a command.

SQLPrepare

Prepares an SQL string for execution.

ct_paramor ct_setparam

Define a command parameter.

SQLBindParameter

Binds a buffer to a parameter marker in an

SQL statement.

ct_send

Sends the command text to the server,

which parses, compiles, and executes it.

SQLExecute

Executes a prepared statement, using the

current values of the parameter marker

variables.

STEP 5: Process The Results Of The STEP 4: Fetch The Results; Fetch The


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Command Row Count

ct_results

Set up result data to be processed.

Defines type of command result:

Values that indicate command status;

Values that indicate fetchable results;

Values that indicate information is

available.

ct_res_info

Retrieve current result set or command

information.

The possible returned information:

The number of the command that

generated the current result set; The number of compute clauses in the

current command;

The number of items in the current

result set;

The number of columns specified in the

order-by clause of the current command;

The number of rows affected by the

current command;

and others.

SQLNumResultCols

Returns the number of columns in a result

set.

If this is 0, the statement did not create a

result set, if it is any other number, the

statement did create a result set.

SQLRowCount

Returns the number of rows affected by an

UPDATE, INSERT, or DELETE statement.

If a batch of SQL statements is executed,

the count of affected rows might be a total

count for all statements in the batch or

individual counts for each statement in the

batch.

ct_describe

Return a description of result data.

An application can use ct_describe to

retrieve a description of a regular result

column, a return parameter, a stored

procedure return status number, or a

compute column.

An application can call ct_res_info to find

out how many result items are present in

the current result set.

An application generally needs to callct_describe to describe a result data item

before it binds the result item to a

program variable using ct_bind.

SQLDescribeCol

Returns the result descriptor column

name, type, column size, decimal digits,

and nullability for one column in the

result set.

ct_bind

Bind server results to program variables

SQLBindCol

Binds application data buffers to columns


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When the application calls ct_fetch to

fetch the result data, it is copied into this

variables.

in the result set.

ct_fetch

Fetch result data.

SQLFetch

Fetches the next rowset of data from the

result set and returns data for all bound

columns.

SQLGetData

Retrieves data for a single column in the

result set. It can be called multiple times

to retrieve variable-length data in parts.

The application now calls SQLFetch to

retrieve the first row of data and place the

data from that row in the variables bound

with SQLBindCol. If there is any long data

in the row, it then calls SQLGetData to

retrieve that data. The application

continues to call SQLFetch and

SQLGetData to retrieve additional data.

After it has finished fetching data, it calls

SQLCloseCursor to close the cursor.

SQLCloseCursor

Closes a cursor that has been opened on a

statement and discards pending results.

STEP 5: Commit The Transaction

The application performs this step only if it

set the transaction commit mode to

manual-commit; if the transaction commit

mode is auto-commit, which is the default,

the transaction is automatically committed

when the statement is executed

SQLEndTran

Requests a commit or rollback operation

for all active operations on all statementsassociated with a connection.

STEP 6: Finish STEP 6: Disconnect From The Data

Source

ct_cmd_drop

Deallocate a command structure.

SQLFreeHandle(STMT)

Free the statement. Driver releases the


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structure used to store information about

the statement.

ct_close

Close a connection.

ct_con_drop

Deallocate connection structure.

SQLDisconnect

Frees any statements that are allocated on

the connection and disconnects the driver

from the data source.

ct_exit

Exit Client-Library for a specific context.

Closes and deallocates any open

connections and cleans up internal Client-

Library data space.

SQLFreeHandle(DBC)

Free the connection. Driver releases the

structure used to store information about

the connection.

cs_ctx_dropDeallocates a context structure.

SQLFreeHandle(ENV)Frees the environment handle. Driver

releases the structure used to store

information about the environment.

Type and structure mapping

The following table displays the correspondence of types and structures of CT-Library to

types and structures of ODBC:

CT-Library ODBC

Structures

CS_CONTEXT

Context structure.

HENV

Environment handle.

CS_CONNECTION

Connection structure.

HDBC

Connection handle.

CS_COMMAND

Command structure.

HSTMT

Statement handle.

Types

Numeric types

CS_TINYINT

tinyint

SQLSCHAR (SQL_C_STINYINT)


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CS_SMALLINT

smallint

SQLSMALLINT (SQL_C_SSHORT)

CS_USMALLINT

usmallint

SQLUSMALLINT (SQL_C_USHORT)

CS_INT

int

SQLINTEGER (SQL_C_SLONG)

CS_UINT

uint

SQLUINTEGER (SQL_C_ULONG)

CS_BIGINT

bigint

SQLBIGINT (SQL_C_SBIGINT)

CS_UBIGINT

ubigint

SQLUBIGINT (SQL_C_UBIGINT)

CS_DECIMAL

decimal

SQL_NUMERIC_STRUCT (SQL_C_NUMERIC)

structure

CS_NUMERIC

numeric


structure

CS_FLOAT

float

SQLDOUBLE, SQLFLOAT (SQL_C_DOUBLE)

CS_REAL

real

SQLREAL (SQL_C_FLOAT)

Money types

CS_MONEY

money


structure

CS_MONEY4smallmoney

SQL_NUMERIC_STRUCT (SQL_C_NUMERIC)structure

Character types

CS_CHAR

char varchar

SQLCHAR (SQL_C_CHAR)

CS_UNICHAR

unichar univarchar

SQLWCHAR (SQL_C_WCHAR)

Datetime types

CS_DATE

date

SQL_DATE_STRUCT (SQL_C_TYPE_DATE)

structureCS_TIME

time

SQL_TIME_STRUCT (SQL_C_TYPE_TIME)

structure

CS_DATETIME

datetime

SQL_TIMESTAMP_STRUCT

(SQL_C_TYPE_TIMESTAMP)

structure

CS_DATETIME4 SQL_TIMESTAMP_STRUCT


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smalldatetime (SQL_C_TYPE_TIMESTAMP)

structure

Bit types

CS_BIT

bit

SQLCHAR (SQL_C_BIT)

Binary types

CS_BINARY

binary varbinary

SQLCHAR (SQL_C_BINARY)

Text and image types

CS_TEXT

text


CS_UNITEXT

unitext

SQLWCHAR (SQL_C_WCHAR)

CS_IMAGE

image



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DB-Library Schema migration

Overview

This section explains mappings and differences between DB-Library and ODBC modules,

commands and types.

Header files mapping

The following table displays the list of required header C files for the use DB-Library and

ODBC API.

DB-Library ODBC

#include

#include

#include

#include

#include

Routine mapping

The following table displays the commands, used in typical execution steps of DB-Library

and ODBC applications, and their correspondence.

DB-Library ODBC

STEP 1: Initialization STEP 1: Connect To The Data Source

dbinit()

Initialize DB-Library.

SQLAllocHandle(ENV)

Load the Driver Manager and allocate theenvironment handle.Driver Manager allocates a structure inwhich to store information about theenvironment, and returns the environmenthandle.

dbsetversion(dbproc, version)

Specify the version level for desiredbehavior.

SQLSetEnvAttr

Sets attributes that govern aspects ofenvironments.

STEP 2: Define Error Handling

dberrhandle(handler)

Install DB-Library error callback function.

dbmsghandle(handler)

Install DB-Library server message callbackfunction.

Replace with SQLGetDiagFieldandSQLGetDiagRecfunction calls in the returncode handlers.

SQLGetDiagField

Returns the current value of a field of a


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record of the diagnostic data structure(associated with a specified handle) thatcontains error, warning, and statusinformation.

SQLGetDiagRec

Returns the current values of multiple fieldsof a diagnostic record that contains error,warning, and status information. UnlikeSQLGetDiagField, which returns onediagnostic field per call, SQLGetDiagRecreturns several commonly used fields of adiagnostic record, including the SQLSTATE,the native error code, and the diagnosticmessage text.

STEP 3: Connect To A Server

dblogin()

Allocate a LOGINREC for use in dbopen.

SQLAllocHandle(DBC)

Allocate a connection handle.Driver Manager allocates a structure inwhich to store information about theconnection and returns the connectionhandle.

DBSETLUSER(loginrec, username)

Set the username in the LOGINRECstructure.

DBSETLPWD(loginrec, password)

Set the user server password in theLOGINREC structure.

DBSETLAPP(loginrec, application)

Set the application name in the LOGINRECstructure.

SQLSetConnectAttr

Sets attributes that govern aspects ofconnections.Some connection attributes must be setbefore the application attempts to connect,

others can be set after the connection hascompleted.

dbopen(loginrec, server)

Connect to a server (and allocate theDBPROCESS).

SQLConnector SQLDriverConnectorSQLBrowseConnectSQLConnect establishes connections to adriver and a data source.

STEP 4: Send A Language Command

To The Server

STEP 2: Initialize The Application

SQLAllocHandle(STMT)

Driver Manager allocates a structure inwhich to store information about thestatement and calls SQLAllocHandle in thedriver with the SQL_HANDLE_STMT option.The driver allocates its own structure in


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which to store information about thestatement and returns the driver statementhandle to the Driver Manager.The Driver Manager returns the DriverManager statement handle.

SQLSetStmtAttr

Sets attributes related to a statement.

STEP 3: Build And Execute An SQL

Statement

dbfcmd(dbproc, string, args...)

Format text and add to the DBPROCESScommand buffer.

dbcmd(dbproc, string)

Add text to the DBPROCESS command

buffer.

dbrpcinit(dbproc, rpc_name, option)

Initialize an RPC.

SQLPrepare

Prepares an SQL string for execution.

dbrpcparam(dbproc, paramname,

status, type, maxlen, datalen, data)

Add a parameter to an RPC.

SQLBindParameter

Binds a buffer to a parameter marker in anSQL statement.

dbsqlexec(dbproc)

Send a command batch to the server for

execution.dbrpcsend(dbproc)

Send an RPC call to the server forexecution.

SQLExecute

Executes a prepared statement, using the

current values of the parameter markervariables.

STEP 5: Process The Results Of The

Command

STEP 4: Fetch The Results; Fetch The

Row Count

dbresults

Sets up the results of the next query.

dbnumaltsReturns the number of columns in acompute row.

dbnumcols

Determines the number of regular columnsfor the current set of results.

dbnumrets

Determines the number of return parameter

SQLNumResultColsReturns the number of columns in a resultset.If this is 0, the statement did not create aresult set, if it is any other number, thestatement did create a result set.

SQLRowCount

Returns the number of rows affected by an


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values generated by a stored procedure.

DBCOUNT

Returns the number of rows affected by aTransact-SQL command.

DBCURCMD

Returns the number of the current logicalcommand.

UPDATE, INSERT, or DELETE statement.If a batch of SQL statements is executed,the count of affected rows might be a totalcount for all statements in the batch orindividual counts for each statement in thebatch.

dbaltlen

Returns the maximum length of the data fora particular compute column.

dbalttype

Returns the datatype for a compute column.

dbaltutype

Returns the user-defined datatype for a

compute column.dbcollen

Returns the maximum length of the data ina regular result column.

dbcolname

Returns the name of a regular resultcolumn.

dbcoltype

Returns the datatype for a regular resultcolumn.

dbcolutype

Returns the user-defined datatype for aregular result column.

dbretname

Determines the name of the storedprocedure parameter associated with aparticular return parameter value.

dbrettype

Determines the datatype of a returnparameter value generated by a storedprocedure.

SQLDescribeCol

Returns the result descriptorcolumnname, type, column size, decimal digits, andnullability for one column in the result set.

dbaltbind, dbaltbind_ps

Binds a compute column to a programvariable.

dbbind, dbbind_ps

Binds a regular result column to a programvariable.

SQLBindCol

Binds application data buffers to columns inthe result set.


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dbnextrow

Reads the next result row.

SQLFetch

Fetches the next rowset of data from theresult set and returns data for all boundcolumns.

SQLGetData

Retrieves data for a single column in theresult set. It can be called multiple times toretrieve variable-length data in parts.The application now calls SQLFetch toretrieve the first row of data and place thedata from that row in the variables boundwith SQLBindCol. If there is any long data inthe row, it then calls SQLGetData to retrievethat data. The application continues to callSQLFetch and SQLGetData to retrieveadditional data.

After it has finished fetching data, it calls

SQLCloseCursor to close the cursor.

SQLCloseCursor

Closes a cursor that has been opened on astatement and discards pending results.

STEP 5: Commit The Transaction

The application performs this step only if itset the transaction commit mode to manual-commit; if the transaction commit mode isauto-commit, which is the default, the

transaction is automatically committed whenthe statement is executed

SQLEndTran

Requests a commit or rollback operation forall active operations on all statementsassociated with a connection.

STEP 6: Cleanup STEP 6: Disconnect From The Data

Source

SQLFreeHandle(STMT)

Free the statement. Driver releases thestructure used to store information about thestatement.

dbclose(dbproc)

Close and deallocate a DBPROCESSstructure.

SQLDisconnect

Frees any statements that are allocated onthe connection and disconnects the driverfrom the data source.


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dbexit()

Close and deallocate all DBPROCESSstructures and clean up any structuresinitialized by dbinit.

SQLFreeHandle(DBC)

Free the connection. Driver releases thestructure used to store information about theconnection.

SQLFreeHandle(ENV)

Frees the environment handle. Driverreleases the structure used to storeinformation about the environment.

Type and structure mapping

The following table displays the correspondence of types and structures of DB-Library to

types and structures of ODBC:

DB-Library ODBC

Structures

LOGINREC

Contains typical logininformation

HDBC

Connection handle

DBPROCESS

Through the DBPROCESS,commands are sent to the

server and query results arereturned to the application

HSTMT

Statement handle

Types

Numeric types

SYBINT1

1-byte integer

SQLSCHAR (SQL_C_STINYINT)

SYBINT2

2-byte integer

SQLSMALLINT (SQL_C_SSHORT)

SYBINT4

4-byte integer

SQLINTEGER (SQL_C_SLONG)

SYBDECIMAL

decimal type


structure

SYBNUMERIC

numeric type


structure

SYBFLT8 SQLDOUBLE, SQLFLOAT (SQL_C_DOUBLE)


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8-byte float type

SYBREAL

4-byte float type

SQLREAL (SQL_C_FLOAT)

Money types

SYBMONEY

money type


structure

SYBMONEY4

4-byte money type


structure

Character types

SYBCHAR

char type


Datetime types

SYBDATETIME

datetime type



structure

SYBDATETIME4

4-byte datetime type



structure

Bit types

SYBBIT

bit type

SQLCHAR (SQL_C_BIT)

Binary types

SYBBINARY

binary type


Text and image types

SYBTEXT

text type


SYBIMAGE

image type



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Other Types of Migration

This section covers migration of several Sybase features related to application programming

and products using connection to Sybase.

Using FreeTDS tool to migrate CT Library and DB Library applications to

SQL Server

FreeTDS libraries can be used for redirecting Sybase client applications to SQL Server.

FreeTDS provides implementations of DB-Library, CT-Library and ODBC driver, allowing many

Sybase client applications that use these interfaces to communicate with Microsoft SQL Server.

You can download the source code for FreeTDS from the Web site (http://www.freetds.org)and

then build, install, and configure it for your target platform.

Take into account that FreeTDS is an open source project and is still very much a work in

progress. Although much of the core functionality is available, you may find it necessary to

either implement any missing functionality in the FreeTDS libraries that your application

requires, or modify your application to avoid these features.

Migration of Open Client Embedded SQL

Sybase Embedded SQL is a superset of Transact-SQL that lets place Transact-SQL statementsin application programs written in C.

Open Client Embedded SQL enables to create programs that access and update Adaptive

Server data. Embedded SQL programmers write SQL statements directly into an application

program written in C. A preprocessing program the Embedded SQL precompiler

processes the completed application program, resulting in a program that the host language

compiler can compile. The program is linked with Open Client Client-Library before it is

executed.

Embedded SQL is one of the two programming methods Sybase provides for accessing

Adaptive Server. The other programming method is the call-level interface. With the call-levelinterface, you place Client-Library calls directly into an application program, then link with Client-

Library.

Embedded SQL statements can be placed anywhere in a host program and mixed with host

language statements. All Embedded SQL statements must begin with the keywords EXEC SQL

and end with a semicolon (;). After you write an Embedded SQL program, run it through the

precompiler, which translates the Embedded SQL statements into Client-Library function calls.
http://www.freetds.org/http://www.freetds.org/http://www.freetds.org/http://www.freetds.org/


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To migrate Sybase C application with Embedded SQL on SQL Server, we suggest replace

Open Client Embedded SQL statements with ODBC routine calls.

Migration of ASE Job Scheduler objects

The SQL Server counterpart of Sybase ASE Job Scheduler is the SQL Server Agent jobs. Like

Sybase Job Scheduler the SQL Server Agent allows you to create and schedule jobs, and to

share jobs and schedules. At the same time SQL Server Agent provides more functionality to

job and schedule management.

You can use SQL Server Agent jobs to automate routine administrative tasks and run them on arecurring basis, making administration more efficient.

A job is a specified series of operations performed sequentially by SQL Server Agent. A job can

perform a wide range of activities, including running Transact-SQL scripts, command-line

applications, Microsoft ActiveX scripts, Integration Services packages, Analysis Services

commands and queries, or Replication tasks. Jobs can run repetitive tasks or those that can be

scheduled, and they can automatically notify users of job status by generating alerts, thereby

greatly simplifying SQL Server administration.

You can run a job manually, or you can configure it to run according to a schedule or in

response to alerts.

Conversion of Transact-SQL statements which are embedded in

applications

You can use the Statements branch in SSMA for Sybase to convert SQL strings embedded in

the user's application code by executing the following steps:

1. In Sybase tree, select the required database and schema and execute Add Statement

command from the Statements branch context menu to create new Statement window.2. Cut the statement from the application (or reconstruct it if the statement is built according

to an algorithm).

3. Paste it into the Statement window.

4. Execute Convert Schema.

5. Paste the result back into the proper place in the application code.


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Temporary tables in code can create problems when their definitions are absent in the module

you are converting. Generally, you should convert the module where a temporary table is

created before converting the modules from which the temporary table is referenced. That way,

SSMA is able to remember the table definition and to use it properly.


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Conclusion

This migration guide can give you some hints about migration of Sybase-based applications to

SQL Server. We discussed typical solutions for most commonly used Sybase application

interfaces.

About DB Best Technologies

DB Best Technologies is a leading provider of database and application migration services and

custom software development. We have been focused on heterogeneous database

environments (SQL Server, Oracle, Sybase, DB2, MySQL) since starting at 2002 in Silicon

Valley. Today, with over 75 employees in the United States and Europe, we develop database

tools and provide services to customers worldwide.

DB Best developed migration tools to automate conversion between SQL dialects. In 2005Microsoft acquired this technology, which later became a family of SQL Server Migration

Assistant (SSMA) products. We continue to develop new versions of SSMA, and support

Microsoft customers who are migrating to SQL Server.

We also provide migration services covering all major steps of a typical migration project:

complexity assessment, schema conversion, data migration, application conversion, testing,

integration, deployment, performance tuning, training, and support.

For more details, visit us at www.dbbest.com, e-mail us at [email protected], or call 1-408-202-

4567.

For more information:

http://www.microsoft.com/sqlserver/:SQL Server Web site

http://technet.microsoft.com/en-us/sqlserver/ :SQL Server TechCenter

http://msdn.microsoft.com/en-us/sqlserver/ :SQL Server DevCenter

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