java prepare_Java PrepareStatement

1.PreparedStatement是预编译的,对于批量处理可以大大提高效率. 也叫JDBC存储过程

2.使用 Statement 对象。在对数据库只执行一次性存取的时侯，用 Statement 对象进行处理。PreparedStatement 对象的开销比Statement大，对于一次性操作并不会带来额外的好处。

3.statement每次执行sql语句，相关数据库都要执行sql语句的编译，preparedstatement是预编译得, preparedstatement支持批处理

用法：

conn = DriverManager.getConnection(url, userName, password);

//创建PreparedStatement语句

PreparedStatement pstmtDelete = conn.prepareStatement(

“DELETE FROM student WHERE stu_id>=?”);

PreparedStatement pstmtInsert = conn.prepareStatement(

“INSERT INTO student VALUES(?, ?, ?, ?)”);

PreparedStatement pstmtSelect = conn.prepareStatement(

“SELECT * FROM student WHERE stu_id>=? ” +

“ORDER BY stu_id”);

int Integer.toString(id));

//多次执行同一语句

for (int i=0; i<3; i++, id++) {

//使用setXXX方法设置IN参数

pstmtDelete.setString(1, Integer.toString(id));

pstmtInsert.setString(1, Integer.toString(id));

pstmtInsert.setString(2, “name”+id);

pstmtInsert.setString(3, “city”+id);

pstmtInsert.setDate(4, new Date(78, 2, id));

//执行PreparedStatement语句

pstmtDelete.executeUpdate();

pstmtInsert.executeUpdate();

ResultSet rs = pstmtSelect.executeQuery();

System.out.println(“”);

System.out.println(“第 ” + (i+1) + ” 次循环后的结果集为：”);

//显示返回的结果集

while (rs.next()) {

String stuID = rs.getString(1);

String String address = rs.getString(3);

String birthday= rs.getString(4);

System.out.println(stuID + ” ” +

name + ” ” + address + ” ” + birthday);

}

}

pstmtDelete.close();

pstmtInsert.close();

pstmtSelect.close();

} catch(SQLException e) {

System.out.println(“出现SQLException异常”);

} finally {

//关闭语句和数据库连接

try {

if (conn != null) conn.close();

} catch(SQLException e) {

System.out.println(“关闭数据库连接时出现异常”);

}

}

}