如何使用JDBC从插入的查询中获取主键值（自动生成的键）？
如果将记录插入到包含自动递增列的表中，请使用Statement或PreparedStatement对象。
您可以使用getGeneratedKeys()方法检索由该对象生成的特定列的值。
示例
让我们使用CREATE语句在MySQL数据库中创建一个名称为sales 的表，其中一列自动递增，如下所示-
CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20), CustomerName VARCHAR (20), DispatchDate date, DeliveryTime time, Price INT, Location VARCHAR(20) );
检索自动生成的值（PreparedStatement对象）
以下JDBC程序使用PreparedStatement将3条记录插入Sales表（上面创建的）中，检索并显示由其生成的自动递增的值。
示例
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Time;
public class RetrievingData_AutoIncrement_Pstmt {
public static void main(String args[]) throws SQLException {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String mysqlUrl = "jdbc:mysql://localhost/sample_database";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//查询以将值插入销售表
String insertQuery = "INSERT INTO Sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) VALUES (?, ?, ?, ?, ?, ?)";
//创建一个PreparedStatement对象
PreparedStatement pstmt = con.prepareStatement(insertQuery,Statement.RETURN_GENERATED_KEYS);
pstmt.setString(1, "Key-Board");
pstmt.setString(2, "Raja");
pstmt.setDate(3, new Date(1567315800000L));
pstmt.setTime(4, new Time(1567315800000L));
pstmt.setInt(5, 7000);
pstmt.setString(6, "Hyderabad");
pstmt.addBatch();
pstmt.setString(1, "Earphones");
pstmt.setString(2, "Roja");
pstmt.setDate(3, new Date(1556688600000L));
pstmt.setTime(4, new Time(1556688600000L));
pstmt.setInt(5, 2000);
pstmt.setString(6, "Vishakhapatnam");
pstmt.addBatch();
pstmt.setString(1, "Mouse");
pstmt.setString(2, "Puja");
pstmt.setDate(3, new Date(1551418199000L));
pstmt.setTime(4, new Time(1551418199000L));
pstmt.setInt(5, 3000);
pstmt.setString(6, "Vijayawada");
pstmt.addBatch();
//执行批处理
pstmt.executeBatch();
//由当前PreparedStatement对象生成的自动递增的值
ResultSet res = pstmt.getGeneratedKeys();
System.out.println("Auto-incremented values of the column ID generated by the current PreparedStatement object: ");
while (res.next()) {
System.out.println(res.getString(1));
}
}
}输出结果
Connection established...... Records inserted...... Auto-incremented values of the column ID generated by the current PreparedStatement object: 1 2 3
检索自动生成的值（Statement对象）
以下JDBC程序使用Statement将3条记录插入Sales表（上面创建的）中，检索并显示由它生成的自动递增的值。
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class RetrievingData_AutoIncrement {
public static void main(String args[]) throws SQLException {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String mysqlUrl = "jdbc:mysql://localhost/sample_database";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//创建Statement对象
Statement stmt = con.createStatement();
//查询插入多行
String insertQuery = "insert into sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) values"
+ "('Key-Board', 'Raja', DATE('2019-09-01'), TIME('11:00:00'), 7000, 'India'), "
+ "('Earphones', 'Roja', DATE('2019-05-01'), TIME('11:00:00'), 2000, 'Vishakhapatnam'), "
+ "('Mouse', 'Puja', DATE('2019-03-01'), TIME('10:59:59'), 3000, 'Vijayawada')";
//执行INSERT语句
stmt.executeUpdate(insertQuery, Statement.RETURN_GENERATED_KEYS);
System.out.println("Records inserted......");
//检索自动生成（自动递增）的键
ResultSet rs = stmt.getGeneratedKeys();
System.out.println("Values of auto-generated keys: ");
while(rs.next()) {
System.out.println(rs.getInt(1));
}
}
}输出结果
Connection established...... Records inserted...... Values of generated keys: 1 2 3