Работа с базами данных – JDBCВведение в JDBC

JDBC

JDBC (Java DataBase Connectivity) – технология доступа к базам данных для Java

Состоит из:• API (java.sql and javax.sql)• Driver Manager• Test Suite + JDBC-ODBC Bridge

JDBC API

• java.sql.Connection• java.sql.Statement (Prepared + Callable)• java.sql.ResultSet• java.sql.*

Driver

Class.forName("com.my.MyDriver");// mydriverConnection conn = DriverManager.getConnection( "jdbc:mydriver:myDatabase",

username,password);

// Class.forName("com.mysql.jdbc.Driver");// "jdbc:mysql://localhost:3306/db_name"

Driver

SQLLectorID FirstName LastName DateOfStart Count

1 Max Tyukh 2013-04-23 4

2 Eugene Bochkov 2013-04-25 4

3 Max Mashnitsky 2013-05-21 5

4 Andrew Grigoruk 2013-06-13 6

SQLConnection conn = DriverManager.getConnection( "jdbc:myDriver:myDatabase", username, password);Statement stmt = conn.createStatement();String q = "SELECT FirstName, LastName, Count FROM Lessions WHERE

Count > 4";ResultSet rs = stmt.executeQuery(q);while (rs.next()) { String f = rs.getString("FirstName"); String l = rs.getFloat("LastName"); int c = rs.getInt("Count"); System.out.println(f + l + " : " + c);}conn.close();

SQL

FirstName LastName Count

Max Mashnitsky 5

Andrew Grigoruk 6

SELECT FirstName, LastName, CountFROM LessionsWHERE Count > 4;

SQLINSERT INTO Lessions(FirstName, LastName, DateOfStart, Count)VALUES('Ivan', 'Petrov', '2013-07-04', 2);

LectorID FirstName LastName DateOfStart Count

1 Max Tyukh 2013-04-23 4

2 Eugene Bochkov 2013-04-25 4

3 Max Mashnitsky 2013-05-21 5

4 Andrew Grigoruk 2013-06-13 6

5 Ivan Petrov 2013-07-04 2

SQL

• Data Manipulation Language (DML)– SELECT, INSERT, DELETE, UPDATE

• Data Definition Language (DDL)– CREATE, DROP, ALTER

• Data Control Language (DCL)– GRANT, REVOKE, DENY

• Transaction Control Language (TCL)– COMMIT, ROLLBACK, SAVEPOINT

Преимущества JDBC

• Изоляция разработки (отсутствие необходимости знать особенностей БД)

• Повторное использование кода• Использование простого клиента (драйвер)• Простота конфигурации (URL + properties)

Q&A