MyBatis框架
5.4 set
- set 主要是用于解決修改操作中SQL語句中可能多出逗號的問題
|
<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> |
5.5 choose(when、otherwise)
- choose 主要是用于分支判斷，類似于java中的switch case,只會滿足所有分支中的一個(gè)
|
<select id="getEmpsByConditionChoose" resultType="com.atguigu.mybatis.beans.Employee"> ????????????? select id ,last_name, email,gender from tbl_employee ????????????? <where> ???????????????????? <choose> ??????????????????????????? <when test="id!=null"> ?????????????????????????????????? id = #{id} ??????????????????????????? </when> ??????????????????????????? <when test="lastName!=null"> ?????????????????????????????????? last_name = #{lastName} ??????????????????????????? </when> ??????????????????????????? <when test="email!=null"> ?????????????????????????????????? email = #{email} ??????????????????????????? </when> ??????????????????????????? <otherwise> ?????????????????????????????????? ?gender = 'm' ??????????????????????????? </otherwise> ???????????????????? </choose> ????????????? </where> </select> |
