mybatis框架中动态SQL的编写

1.动态SQL：在SQL语句中加入流程控制。比如加入if，foreach等。

 重点掌握if语句：

 案例1：

<update id="updateItem" parameterType="com.gxa.bj.model.UserInfo">

         update userinfo set

         <if test="userName!=null">

             userName = #{userName},

         </if>

         <if test="userPwd!=null">

             userPwd = #{userPwd},

         </if>

         <if test= "userEmail!=null">

             userEmail = #{userEmail},

         </if>

         <if test= "userAddress!=null">

             userAddress = #{userAddress},

         </if>

         <if test= "regReason!=null">

            regReason = #{regReason},

         </if>

          userId=#{userId} Where userId=#{userId}

   </update>

案例2：

<select id="getList" parameterType="com.gxa.bj.model.UserInfo" resultType="com.gxa.bj.model.UserInfo">

        Select * From userInfo Where 1=1

        <if test="userName!=null">

            And userName like #{userName}

        </if>

        <if test="userId>0">

            And userId =#{userId}

        </if>

        <if test="userPwd!=null And userPwd!=''">

            And userPwd like #{userPwd}

        </if>

        

   </select>