14-Mybatis中like使用的两种情况

前一篇：13-Mybatis封装输出结果之二 – resultMap
https://blog.csdn.net/fsjwin/article/details/109674185

模糊查询，在mybaits中有两种实现方式

1.在java代码中准备好字符串

1.1StudentDao

//使用名字like
    public Student selectStudentlike1(String name);

1.2StudentDao.xml

<select id="selectStudentlike1"  resultType="com.yuhl.domain.Student">
        select id,name,email,age from student where name like #{name}
    </select>

1.3测试

    @Test
    public void test16() {
        SqlSession sqlsession = MybatisUtil.getSqlsession();
        StudentDao studentDao = sqlsession.getMapper(StudentDao.class);
        //可以吧查询的条件放进去，也可以使用一个单独的类ParaObject类封装就可以了。
        Student student = studentDao.selectStudentlike1("%张%");
        System.out.println(student);
    }

1.4测试结果

Checking to see if class com.yuhl.vo.StudentVo matches criteria [is assignable to Object]
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 188576144.
==>  Preparing: select id,name,email,age from student where name like ?
==> Parameters: %张%(String)
<==    Columns: id, name, email, age
<==        Row: 1001, 张三, [e-mail], 20
<==      Total: 1
Student{id=1001, name='张三', email='[e-mail]', age=20}

2.在mapper中进行拼接

2.1StudentDao

    //使用名字like
    public Student selectStudentlike2(String name);

2.2StudentDao.xml

 <select id="selectStudentlike2"  resultType="com.yuhl.domain.Student">
        select id,name,email,age from student where name like "%" #{name} "%"
    </select>

2.3测试

@Test
    public void test17() {
        SqlSession sqlsession = MybatisUtil.getSqlsession();
        StudentDao studentDao = sqlsession.getMapper(StudentDao.class);
        //可以吧查询的条件放进去，也可以使用一个单独的类ParaObject类封装就可以了。
        Student student = studentDao.selectStudentlike2("张");
        System.out.println(student);
    }

2.4测试结果

Checking to see if class com.yuhl.vo.StudentVo matches criteria [is assignable to Object]
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 188576144.
==>  Preparing: select id,name,email,age from student where name like "%" ? "%"
==> Parameters: 张(String)
<==    Columns: id, name, email, age
<==        Row: 1001, 张三, [e-mail], 20
<==      Total: 1
Student{id=1001, name='张三', email='[e-mail]', age=20}

3.总结

使用这两种方式均可以处模糊查询，推荐第一种

1. 在java代码中准备好字符串
2. 在mapper中进行拼接

脑图https://www.processon.com/view/link/5fae2e01f346fb2d03b384d3

下一篇：15-Mybatis动态sql之一 – ＜if＞标签https://blog.csdn.net/fsjwin/article/details/109675572