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Работа с базами данных – JDBC
Введение 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");
// mydriver
Connection conn = DriverManager.getConnection(
"jdbc:mydriver:myDatabase",
username,password);
// Class.forName("com.mysql.jdbc.Driver");
// "jdbc:mysql://localhost:3306/db_name"
Driver
SQL
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
SQL
Connection 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
SELECT FirstName, LastName, Count
FROM Lessions
WHERE Count > 4;
FirstName
LastName
Count
Max
Mashnitsky
5
Andrew
Grigoruk
6
SQL
INSERT 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