preparedstatement运行sql语句时，set函数后面的类型用什么来决定？
发布网友
发布时间：2022-04-09 08:01
我来回答
共2个回答
懂视网
时间：2022-04-09 12:22
java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import org.junit.Test;
import util.JdbcUtil;
/**
* PreparedStatement執行sql語句
* @author APPle
*
*/
public class Demo1 {
/**
* 增加
*/
@Test
public void testInsert() {
Connection conn = null;
PreparedStatement stmt = null;
try {
//1.获取连接
conn = JdbcUtil.getConnection();
//2.准备预编译的sql
String sql = "INSERT INTO student2(NAME,gender) VALUES(?,?)"; //?表示一个参数的占位符
//3.执行预编译sql语句(检查语法)
stmt = conn.prepareStatement(sql);
//4.设置参数值
/**
* 参数一： 参数位置 从1开始
*/
stmt.setString(1, "李四");
stmt.setString(2, "男");
//5.发送参数，执行sql
int count = stmt.executeUpdate();
System.out.println("影响了"+count+"行");
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
JdbcUtil.close(conn, stmt);
}
}
/**
* 修改
*/
@Test
public void testUpdate() {
Connection conn = null;
PreparedStatement stmt = null;
try {
//1.获取连接
conn = JdbcUtil.getConnection();
//2.准备预编译的sql
String sql = "UPDATE student2 SET NAME=? WHERE id=?"; //?表示一个参数的占位符
//3.执行预编译sql语句(检查语法)
stmt = conn.prepareStatement(sql);
//4.设置参数值
/**
* 参数一： 参数位置 从1开始
*/
stmt.setString(1, "王五");
stmt.setInt(2, 9);
//5.发送参数，执行sql
int count = stmt.executeUpdate();
System.out.println("影响了"+count+"行");
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
JdbcUtil.close(conn, stmt);
}
}
/**
* 删除
*/
@Test
public void testDelete() {
Connection conn = null;
PreparedStatement stmt = null;
try {
//1.获取连接
conn = JdbcUtil.getConnection();
//2.准备预编译的sql
String sql = "DELETE FROM student2 WHERE id=?"; //?表示一个参数的占位符
//3.执行预编译sql语句(检查语法)
stmt = conn.prepareStatement(sql);
//4.设置参数值
/**
* 参数一： 参数位置 从1开始
*/
stmt.setInt(1, 9);
//5.发送参数，执行sql
int count = stmt.executeUpdate();
System.out.println("影响了"+count+"行");
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
JdbcUtil.close(conn, stmt);
}
}
/**
* 查询
*/
@Test
public void testQuery() {
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
//1.获取连接
conn = JdbcUtil.getConnection();
//2.准备预编译的sql
String sql = "SELECT * FROM student2";
//3.预编译
stmt = conn.prepareStatement(sql);
//4.执行sql
rs = stmt.executeQuery();
//5.遍历rs
while(rs.next()){
int id = rs.getInt("id");
String name = rs.getString("name");
String gender = rs.getString("gender");
System.out.println(id+","+name+","+gender);
}
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
//关闭资源
JdbcUtil.close(conn,stmt,rs);
}
}
}
PreparedStatement執行sql語句
标签：
热心网友
时间：2022-04-09 09:30
你指的是问号占位符，后面类型有数据库里字段决定
