写一个java的增删改查
时间: 2023-03-19 11:25:19 浏览: 104
好的,以下是Java语言实现的增删改查的示例代码:
增加数据:
```java
//假设需要向名为"users"的表中添加一条记录,记录的内容为:{"id": 1, "name": "张三", "age": 20}
String sql = "insert into users(id, name, age) values(1, '张三', 20)";
PreparedStatement pstmt = conn.prepareStatement(sql);
int result = pstmt.executeUpdate();
if (result > 0) {
System.out.println("插入成功!");
} else {
System.out.println("插入失败!");
}
```
删除数据:
```java
//假设需要从名为"users"的表中删除一条id为1的记录
String sql = "delete from users where id = ?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, 1);
int result = pstmt.executeUpdate();
if (result > 0) {
System.out.println("删除成功!");
} else {
System.out.println("删除失败!");
}
```
修改数据:
```java
//假设需要将名为"users"的表中id为1的记录的name改为"李四",age改为22
String sql = "update users set name = ?, age = ? where id = ?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, "李四");
pstmt.setInt(2, 22);
pstmt.setInt(3, 1);
int result = pstmt.executeUpdate();
if (result > 0) {
System.out.println("修改成功!");
} else {
System.out.println("修改失败!");
}
```
查询数据:
```java
//假设需要从名为"users"的表中查询所有记录的id、name、age字段
String sql = "select id, name, age from users";
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
while (rs.next()) {
int id = rs.getInt("id");
String name = rs.getString("name");
int age = rs.getInt("age");
System.out.println("id: " + id + ", name: " + name + ", age: " + age);
}
```