oracle - the basic select
DESCRIPTION
Oracle - The basic SelectTRANSCRIPT
![Page 1: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/1.jpg)
1
The Basic SQL SELECT Statement
![Page 2: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/2.jpg)
2
Objectives
• List the capabilities of SQL SELECT statements• Execute a basic SELECT statement• Differentiate between SQL statements and
iSQL*Plus commands
![Page 3: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/3.jpg)
3
Capabilities of SQL SELECT Statements
Selection(Restriction)Projection
Table 1 Table 2
Table 1Table 1
Join
![Page 4: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/4.jpg)
4
Basic SELECT Statement
SELECT *|{[DISTINCT] column|expression [alias],...}FROM table;
• SELECT identifies what columns• FROM identifies which table
![Page 5: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/5.jpg)
5
SELECT *FROM departments;
Selecting All Columns
![Page 6: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/6.jpg)
6
Selecting Specific Columns
SELECT department_id, location_idFROM departments;
![Page 7: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/7.jpg)
7
Writing SQL Statements
• SQL statements are not case sensitive. • SQL statements can be on one or more lines.• Keywords cannot be abbreviated or split
across lines.• Clauses are usually placed on separate lines.• Indents are used to enhance readability.
![Page 8: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/8.jpg)
8
Column Heading Defaults
• iSQL*Plus:– Default heading justification: Center– Default heading display: Uppercase
• SQL*Plus:– Character and Date column headings are left-
justified– Number column headings are right-justified– Default heading display: Uppercase
![Page 9: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/9.jpg)
9
Arithmetic Expressions
Create expressions with number and date data by using arithmetic operators.
Operator
+
-
*
/
Description
Add
Subtract
Multiply
Divide
![Page 10: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/10.jpg)
10
Operator Precedence
• Multiplication and division take priority over addition and subtraction.
• Operators of the same priority are evaluated from left to right.
• Parentheses are used to force prioritized evaluation and to clarify statements.
** // ++ __
![Page 11: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/11.jpg)
11
Operator Precedence
SELECT last_name, salary, 12*salary+100FROM employees;
…
![Page 12: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/12.jpg)
12
Using Parentheses
SELECT last_name, salary, 12*(salary+100)FROM employees;
…
![Page 13: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/13.jpg)
13
Defining a Null Value
• A null is a value that is unavailable, unassigned, unknown, or inapplicable.
• A null is not the same as zero or a blank space.SELECT last_name, job_id, salary, commission_pctFROM employees;
…
…
![Page 14: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/14.jpg)
14
SELECT last_name, 12*salary*commission_pctFROM employees;
Null Values in Arithmetic Expressions
Arithmetic expressions containing a null value evaluate to null.
…
…
![Page 15: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/15.jpg)
15
Defining a Column Alias
A column alias:• Renames a column heading• Is useful with calculations• Immediately follows the column name - there
can also be the optional AS keyword between the column name and alias
• Requires double quotation marks if it contains spaces or special characters or is case sensitive
![Page 16: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/16.jpg)
16
Using Column Aliases
SELECT last_name "Name", salary*12 "Annual Salary"FROM employees;
SELECT last_name AS name, commission_pct commFROM employees;
…
…
![Page 17: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/17.jpg)
17
Concatenation Operator
A concatenation operator:• Concatenates columns or character strings to
other columns • Is represented by two vertical bars (||)• Creates a resultant column that is a character
expression
![Page 18: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/18.jpg)
18
Using the Concatenation Operator
SELECT last_name||job_id AS "Employees"FROM employees;
…
![Page 19: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/19.jpg)
19
Literal Character Strings
• A literal is a character, a number, or a date included in the SELECT list.
• Date and character literal values must be enclosed within single quotation marks.
• Each character string is output once for eachrow returned.
![Page 20: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/20.jpg)
20
Using Literal Character Strings
SELECT last_name ||' is a '||job_id AS "Employee Details"FROM employees;
…
![Page 21: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/21.jpg)
21
Duplicate Rows
The default display of queries is all rows, including duplicate rows.
SELECT department_idFROM employees;
…
![Page 22: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/22.jpg)
22
Eliminating Duplicate Rows
Eliminate duplicate rows by using the DISTINCT keyword in the SELECT clause.SELECT DISTINCT department_idFROM employees;
![Page 23: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/23.jpg)
23
SQL and iSQL*Plus/Sql*Plus Interaction
SQL statementsOracleserver
Query resultsQuery resultsiSQL*Plus commands
Client
Formatted report
Internet Internet BrowserBrowser
iiSQL*PlusSQL*Plus
![Page 24: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/24.jpg)
24
SQL Statements Versus iSQL*Plus Commands
SQLSQLstatementsstatements
SQL • A language• ANSI standard• Keyword cannot be
abbreviated• Statements manipulate
data and table definitions in the database
iiSQL*PlusSQL*Plus• An environment• Oracle proprietary• Keywords can be
abbreviated• Commands do not allow
manipulation of values in the database
• Runs on a browser• Centrally loaded, does not
have to be implemented on each machine
iiSQL*PlusSQL*Pluscommandscommands
![Page 25: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/25.jpg)
25
Overview of iSQL*Plus
After you log into iSQL*Plus, you can:• Describe the table structure• Edit your SQL statement• Execute SQL from iSQL*Plus• Save SQL statements to files and append SQL
statements to files• Execute statements stored in saved files• Load commands from a text file into the
iSQL*Plus Edit window
![Page 26: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/26.jpg)
26
Logging In to iSQL*Plus
From your Windows browser environment:
![Page 27: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/27.jpg)
27
The iSQL*Plus Environment
3 4 5
6
71
2
8 910
![Page 28: Oracle - the Basic Select](https://reader034.vdocuments.mx/reader034/viewer/2022042721/577cc0b81a28aba71190ddd9/html5/thumbnails/28.jpg)
28
Summary
SELECT *|{[DISTINCT] column|expression [alias],...}FROM table;
In this lesson, you should have learned how to: • Write a SELECT statement that:
– Returns all rows and columns from a table– Returns specified columns from a table– Uses column aliases to give descriptive column
headings
• Use the iSQL*Plus environment to write, save, and execute SQL statements and iSQL*Plus commands.