MyBatis框架
5.3 trim
- Trim 可以在条件判断完的SQL语句前后 添加或者去掉指定的字符
prefix: 添加前缀
prefixOverrides: 去掉前缀
suffix: 添加后缀
suffixOverrides: 去掉后缀
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<select id="getEmpsByConditionTrim" resultType="com.atguigu.mybatis.beans.Employee"> select id , last_name ,email , gender from tbl_employee <trim prefix="where" suffixOverrides="and"> <if test="id!=null"> id = #{id} and </if> <if test="lastName!=null && lastName!="""> last_name = #{lastName} and </if> <if test="email!=null and email.trim()!=''"> email = #{email} and </if> <if test=""m".equals(gender) or "f".equals(gender)"> gender = #{gender} </if> </trim> </select> |
5.4 set
- set 主要是用于解决修改操作中SQL语句中可能多出逗号的问题
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<update id="updateEmpByConditionSet"> update tbl_employee <set> <if test="lastName!=null && lastName!="""> last_name = #{lastName}, </if> <if test="email!=null and email.trim()!=''"> email = #{email} , </if> <if test=""m".equals(gender) or "f".equals(gender)"> gender = #{gender} </if> </set> where id =#{id} </update> |
