Common techniques for Java database programming

Java database Operation basic process: Get database connection-Execute SQL statement-Process Execution result-release database connection

1. Get the database connection

1 Use DriverManager to access the database connection, example:

String className,url,uid,pwd;
className = "oracle.jdbc.driver.OracleDriver";
url = "jdbc:oracle:thin:@127.0.0.1:1521:orasvr;
uid = "system";
pwd = "manager";
Class.forName(className);
Connection cn = DriverManager.
getConnection(url,uid,pwd);

2) using Jndi (Java naming and directory services), examples:

String jndi = "jdbc/db";
　　Context ctx =
(Context) new InitialContext().lookup　
("Java:comp/env");
　　DataSource ds = (DataSource) ctx.lookup(jndi);
　　Connection cn = ds.getConnection();

More used in JSP

2. Execute SQL statement

1 using statement to execute SQL statements

String sql;
Statement sm = cn.createStatement();
sm.executeQuery(sql);
// 执行数据查询语句（select）
sm.executeUpdate(sql);
// 执行数据更新语句
（delete、update、insert、drop等）
statement.close();

2 using PreparedStatement to execute SQL statements

String sql;
sql = "insert into user (id,name) values (?,?)";
PreparedStatement ps = cn.prepareStatement(sql);
ps.setInt(1,xxx);
ps.setString(2,xxx);
...
ResultSet rs = ps.executeQuery();
// 查询
int c = ps.executeUpdate();
// 更新