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Mybatis - dynamic SQL statement - if usage - MySQL series learning notes

select

Based on the parameters passed in : If the user name is not empty , Then fuzzy query is performed on the user name , If the mailbox is not empty , Then take the mailbox as the query criteria

    <select id="selectByUser" parameterType="com.tgb.mybatis.entity.SysUser" resultType="com.tgb.mybatis.entity.SysUser">
        select
            user_name "userName",
            user_password "userPassword",
            user_info "userInfo",
            head_img	"headImg",
            create_time "createTime"
        from
            sys_user
        where
            1=1
            <if test="userName != null and userName !=''">
              and user_name like CONCAT('%',#{userName},'%')
            </if>
            <if test="userEmail != null and userEmail != ''">
              and user_email =#{userEmail}
            </if>
    </select>

update

find id by xxx This data , Attribute by attribute judgment , If the attribute is not empty , Then update

    <update id="updateById">
        update sys_user
            SET
              <if test="userName != null and userName !=''">
                user_name = #{userName},
              </if>
              <if test="userPassword != null and userPassword !=''">
                user_password = #{userPassword},
              </if>
              <if test="userEmail != null and userEmail !=''">
                user_email = #{userEmail},
              </if>
              <if test="userInfo != null and userInfo !=''">
                user_info = #{userInfo},
              </if>
              <if test="headImg != null and headImg !=''">
                head_img = #{headImg},
              </if>
              <if test="createTime != null and createTime !=''">
                create_time =#{createTime},
              </if>
              id = #{id}
            where
                id = #{id}
    </update>

insert

    <insert id="insert">
        insert into sys_user(
          user_name,
          user_password,
          <if test="userEmail !=null and userEmail != ''">
              user_email,
          </if>
          user_info,
          head_img,
          create_time
        )
        VALUES
        (#{userName},
         #{userPassword},
        <if test="userEmail != null and userEmail !=''">
            user_email = #{userEmail},
        </if>
        #{userInfo},
        #{headImg, jdbcType=BLOB},
        #{createTime,jdbcType=TIMESTAMP})
    </insert>

About where1=1 Application , See my blog ——> Let's go to Dachang series 】 In depth understanding of MySQL in where 1 = 1 Usefulness

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