标签：结果 commit each 比较 参数类型 set ctp color override
1.动态sql-if
当有值输入才进行sql的动态拼接
<!-- 动态sql-if--> <select id="selectPersonByName" resultType="Person"> select * from `person` where `age` > #{age} <if test="value != null and value != ‘‘"> and `name` like ‘%${value}%‘ </if> </select>
/*动态sql-if测试*/
@Test
public void selectPersonByName() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
List<Person> persons = personMapper.selectPersonByName(5,"四");
sqlSession.close();
System.out.println(persons);
}
2.choose-when-otherwise
<!-- 动态sql choose-when-otherwise --> <!-- when 当有匹配时候执行拼接， 都没有匹配时，拼接otherwise （和 switch case 意思相近）--> <select id="selectPersonByAgeOrName" parameterType="Person" resultType="Person"> select * from `person` where `id` > 0 <choose> <when test="name != null and name != ‘‘"> and name like #{name} </when> <when test="age != null and age != ‘‘"> and age > #{age} </when> <otherwise> and `age`>`id` </otherwise> </choose> </select>
/*<!-- 动态sql choose-when-otherwise -->*/
@Test
public void selectPersonByAgeOrName() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
Person person = new Person();
//person.setName("%四%");
List<Person> persons = personMapper.selectPersonByAgeOrName(person);
sqlSession.close();
System.out.println(persons);
}
3.sql-where (前面写的where `id` > 0比较无脑， 但是 不写会出现sql语法错误)
<!-- 动态sql where--> <!-- 第一个if中 不写and 后面的if中必须写 --> <select id="selectPersonByNameOrAge" parameterType="Person" resultType="Person"> select * from person <where> <if test="name != null and name != ‘‘"> `name` like #{name} </if> <if test="age != null and age != 0"> and `age` = #{age} </if> </where> </select>
/*<!-- 动态sql where -->*/
@Test
public void selectPersonByNameOrAge() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
Person person = new Person();
person.setName("%五%");
person.setAge(11);
Person persons = personMapper.selectPersonByNameOrAge(person);
sqlSession.close();
System.out.println(persons);
}
4.动态sql-set
<!-- 动态sql set--> <!-- 避免先查询再修改，只修改指定列 --> <update id="updatePersonByCondition" parameterType="Person"> UPDATE `person` <set> <if test="name != null and name != ‘‘">`name` = #{name} ,</if> <if test="age != null and age != 0"> `age`=#{age} </if> </set> WHERE (`id`=#{id}) </update>
/*<!-- 动态sql set-->*/
@Test
public void updatePersonByCondition() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
Person person = new Person("王炸",50);
person.setId(3);
int count = personMapper.updatePersonByCondition(person);
sqlSession.commit();
sqlSession.close();
System.out.println("更新了 count = " + count + "条记录");
}
5.sql-trim (加前缀，去掉多余的部分 可以替换sql-set 特可以替换 sql-where 使用灵活)
<!-- 动态sql trim--> <select id="selectPersonByNameOrAgeTrim" parameterType="Person" resultType="Person"> select * from person <trim prefix="where" suffixOverrides="or | and"> <!-- 与where作用一样 prefix 加前缀，suffixOverrides 去掉多余的 --> <if test="name != null and name != ‘‘"> `name` like #{name} </if> <if test="age != null and age != 0"> and `age` = #{age} </if> </trim> </select>
@Test
public void selectPersonByNameOrAgeTrim() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
Person person = new Person();
person.setName("%h%");
List<Person> persons = personMapper.selectPersonByNameOrAgeTrim(person);
sqlSession.close();
System.out.println(persons);
}
6.sql-foreach
<!-- 动态sql foreach--> <delete id="deletePersonList" parameterType="list"> delete from `person` where id in <foreach collection="list" item="id" open="(" separator="," close=")"> <!--<foreach collection="传递进来的参数类型 如list arra" item="迭代变量，随意" open="开始符号" separator="分割符号" close="结束符号"> 执行结果 (1,2,3) --> #{id} </foreach> </delete>
@Test
public void deletePersonList() {
SqlSession sqlSession = MybatisUtil.getSqlSession();
PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
List<Integer> idList = new ArrayList<>();
idList.add(2);
idList.add(5);
int count = personMapper.deletePersonList(idList);
sqlSession.commit();
sqlSession.close();
System.out.println("删除记录 count = " + count);
}
标签：结果 commit each 比较 参数类型 set ctp color override
原文地址：https://www.cnblogs.com/xfishs/p/9849027.html
