java处理数据库的CRUD
时间：2021-07-01 10:21:17
帮助过：2人阅读
com.lhy.jdbc.util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
/**
*
* 增删改查
* @author hy
*
*/
public class CRUD {
public static void main(String[] args) {
//create();
//read();
//update();
delete();
}
/**
* 查询
*/
static void read() {
Connection conn =
null;
Statement stmt =
null;
ResultSet rs =
null;
try {
// 建立连接，JdbcUtil工具类请看我的另一篇博客
conn =
JdbcUtil.getConnection();
// 创建语句
stmt =
conn.createStatement();
/**
* 执行语句,一般不建议直接写select *，可读性不好。
*/
rs = stmt.executeQuery("select * from user"
);
// 处理结果
while (rs.next()) {
System.out.println(rs.getString("username") + "\t"
+ rs.getString("password"
));
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtil.close(rs);
JdbcUtil.close(stmt);
JdbcUtil.close(conn);
}
}
/**
* insert into插一条记录
*/
static void create(){
Connection conn =
null;
Statement stmt =
null;
try {
// 建立连接
conn =
JdbcUtil.getConnection();
// 创建语句
stmt =
conn.createStatement();
String sql = "insert into user values(‘你好‘,‘147‘,1000)"
;
//执行语句,返回值是int 几行被插入
stmt.executeUpdate(sql);
//int i = stmt.executeUpdate(sql);
//System.out.println("i="+i);
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtil.close(stmt);
JdbcUtil.close(conn);
}
}
/**
* 更新
*/
static void update(){
Connection conn =
null;
Statement stmt =
null;
try {
// 建立连接
conn =
JdbcUtil.getConnection();
// 创建语句
stmt =
conn.createStatement();
// 执行语句
String sql = "update user set money = money + 100"
;
// int i =
stmt.executeUpdate(sql);
// System.out.println("i="+
i);
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtil.close(stmt);
JdbcUtil.close(conn);
}
}
static void delete(){
Connection conn =
null;
Statement stmt =
null;
try {
// 建立连接
conn =
JdbcUtil.getConnection();
// 创建语句
stmt =
conn.createStatement();
// 执行语句
String sql = "delete from user where money <600"
;
int i =
stmt.executeUpdate(sql);
System.out.println("i="+
i);
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtil.close(stmt);
JdbcUtil.close(conn);
}
}
}
java处理数据库的CRUD
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