mybatis的动态sql之if test的使用说明

<select parameterType='java.lang.String' resultType='java.lang.String'> SELECT MAX(DEPART_ID) FROM T_P_DEPART <where> <if test='_parameter!=null and _parameter!=’’'> AND DEPART_PID = #{departId,jdbcType=VARCHAR} </if> <if test='_parameter==null or _parameter==’’'> AND DEPART_PID IS NULL </if> </where> </select>参数为pojo , if test读取该参数代码

<select parameterType='ShopVo' resultType='ShopCustomer'> select * from shop <where> <if test='shopCustomer.shopname!=null and shopCustomer.shopname!=’’'>shop.shopname like ’%${shopCustomer.shopname}%’ </if> <if test='shopCustomer.shopname==null or shopCustomer.shopname==’’'> AND shop.shopname is null </if> </where></select>

补充：关于mybatis中 if test的条件怎么写

<if test='title != null'> AND title like #{title}</if>

参考官方文档:

实际项目中会有这种情况: 页面上title字段输入某个值进行查询,手动将输入框中的值删除,然后再次查询,发现结果不正确,究其原因是应为title传入了空串' ' 这样在mybatis配置文件中就会用空串进行查询,导致出现错误结果

<if test='title != null and title != ’’' > AND title like #{title}</if>2.使用mybatis 做修改时将字段置空

if中如果传入的参数如果为空,那么将不会执行if中的语句

<update parameterType='*.*.Object' >update table <set> <if test='Object.fullName == null or Object.fullName ==’’'> full_name = null, </if> <if test='Object.fullName != null and Object.fullName !=’’'> full_name = #{companyOrg.fullName}, </if> <if test='Object.level == null or Object.level ==’’'> level = null, </if> <if test='Object.level == 0 '> level = null, </if> <if test='Object.level != null and Object.level !=’’ and Object.level != 0 '> level = #{companyOrg.level}, </if> </set> where 1=1 and id =#{companyOrg.id}</update>

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