import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

import org.junit.Test;


public class JDBCTest {

/**
* 获取数据库自动生成的主键
* */
@Test
public void testGetkeyValue() {
Connection connection = null;
PreparedStatement preparedStatement = null;
try {
connection =  JDBCTools.getConnection();
String sql = "insert into examstudent(student_name,location,grade) "
+ "values(?,?,?) ";
//preparedStatement = connection.prepareStatement(sql);

//使用重载的prepareStatement(sql,flag)
//来生成prepareStatement对象
preparedStatement = connection.prepareStatement(sql,
Statement.RETURN_GENERATED_KEYS);
preparedStatement.setString(1, "TOM");
preparedStatement.setString(2, "SHENZHEN");
preparedStatement.setInt(3, 98);

preparedStatement.executeUpdate();

//通过preparedStatement的。getGeneratedKeys()方法获取包含了新生成的主键的ResultSet对象
ResultSet rs = preparedStatement.getGeneratedKeys();
if(rs.next()){
System.out.println(rs.getObject(1));
}
ResultSetMetaData rsmd = rs.getMetaData();
for(int i = 0; i<rsmd.getColumnCount(); i++){
System.out.println(rsmd.getColumnName(i+1));
}
} catch (Exception e) {
e.printStackTrace(); }
}

}