学习IDEA连接MySQL数据库（实现增删改查）1、在测试类testDbUtil.java编写测试⽅法:
增加：
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@Test
public void testInsert(){
try{
Connection conn = Connection();
String sql ="INSERT INTO band(name,remark) VALUES(?,?)";
PreparedStatement pstmt = conn.prepareStatement(sql);//sql语句预处理
pstmt.setString(1,"软⼯1班");
pstmt.setString(2,"备注信息");
int result = uteUpdate();
if(result>0){
System.out.println("添加成功");
}else{
System.out.println("添加失败");
}
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
在运⾏代码前这是之前添加的两条记录：
运⾏后，添加了跳记录：
修改（按i条件为d进⾏修改）：
@Test
public void testUpdate(){
try{distinct 编程语句
Connection conn = Connection();
String sql ="UPDATE band set name=?,remark=? WHERE id=?";
PreparedStatement pstmt = conn.prepareStatement(sql);//sql语句预处理        pstmt.setString(1,"软⼯2班");
pstmt.setString(2,"备注信息2");
pstmt.setInt(3,5);
int result = uteUpdate();
if(result>0){
System.out.println("修改成功");
}else{
System.out.println("修改失败");
}
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
运⾏代码后id为5的记录被修改了：
删除（按条件id进⾏删除）：
@Test
public void testDelete(){
try{
Connection conn = Connection();
String sql ="DELETE FROM band WHERE id=?";
PreparedStatement pstmt = conn.prepareStatement(sql);//sql语句预处理            pstmt.setInt(1,5);
int result = uteUpdate();
if(result>0){
System.out.println("删除成功");
}else{
System.out.println("删除失败");
}
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
运⾏代码后id为5的记录被删除了：
查询（查询全部记录）：
@Test
public void testFindAll(){
try{
Connection conn = Connection();
String sql ="SELECT * FROM band";
PreparedStatement pstmt = conn.prepareStatement(sql);//sql语句预处理          ResultSet rs = uteQuery();
()){
int id = rs.getInt("id");
String name = rs.getString("name");
String  remark = rs.getString("remark");
System.out.println(id+","+name+","+remark);
}
rs.close();
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
运⾏代码后我们可以看到全部记录：
查询（按id进⾏查询）：
@Test
public void testFindById(){
try{
Connection conn = Connection();
String sql ="SELECT * FROM band WHERE id=?";
PreparedStatement pstmt = conn.prepareStatement(sql);//sql语句预处理          pstmt.setInt(1,1);
ResultSet rs = uteQuery();
()){win10python安装教程
int id = rs.getInt("id");maven依赖排除
String name = rs.getString("name");
String  remark = rs.getString("remark");
System.out.println(id+","+name+","+remark);
}
rs.close();
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
查询id=1，运⾏代码后如下：
mysql菜鸟教程增删改查
查询（按通配字符%惊醒查询）：
@Test
public void testFindByName(){
try{
Connection conn = Connection();
String sql ="SELECT * FROM band WHERE name LIKE ?";
PreparedStatement pstmt = conn.prepareStatement(sql);//sql语句预处理            pstmt.setString(1,"%2%");
ResultSet rs = uteQuery();
()){
int id = rs.getInt("id");
String name = rs.getString("name");
String  remark = rs.getString("remark");
System.out.println(id+","+name+","+remark);
}
rs.close();
pstmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
}
}
>java事务隔离的四个级别

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