mybatis中的常见动态sql语句

mybatis中的常见动态sql语句( 增删改查)

开发中写sql语句的增删改查是不可避免的，但只写单一sql语句，复用性不强，所以此时可以写动态sql。这里列举开发中常写的四种动态sql ，当做笔记以后直接拿。

1.查询

 // 接口
 public List<Map<String,Object>>  getPerformScoreList(ScoringStandardVO scoringStandardVO);

<select id="getPerformScoreList" resultType="java.util.Map">
       SELECT
           es.PER_ID  AS perId ,
           es.PER_NAME AS perName ,
           date_format(es.UPDATE_TIME,'%Y-%m-%d') AS updateTime,  ps: 时间类型，展示 年月日
           es.`STATUS` AS status       ps:(注意最后没有逗号)
       FROM ACT_RU_TASK ART
       LEFT JOIN ACT_RU_IDENTITYLINK ARI ON ARI.TASK_ID_ = ART.ID_
       LEFT JOIN evaluation_scheme_sun ess ON ess.sun_business_id = AHP.BUSINESS_KEY_
       <where>
           <if test="perName != null and perName != ''">
               es.PER_NAME LIKE CONCAT('%',#{perName},'%')
           if>
           <if test="status != null and status != ''">
                AND status= #{status}
           if>
           <if test="createTime != null ">      ps:注意时间类型比较时，不能写 != "" ,空是字符串类型。
                AND TO_DAYS(es.CREATE_TIME)= TO_DAYS(#{createTime})
           if>
           <if test="createTime != null ">
           		AND convert(date,su.LOCK_TIME) >= convert(date,#{lockTime})
           if>
           <if test="taskKeyList != null and taskKeyList.size > 0">
               AND es.task_key in
               <foreach collection="taskKeyList" item="key" open="(" close=")" separator=",">
                   #{key}
               foreach>
           if>
           AND (( ARI.TYPE_ = 'candidate'
           AND ARI.USER_ID_ = #{userId})
           OR ART.ASSIGNEE_ = #{userId})
       where>
       ORDER BY es.CREATE_TIME ASC 
       <trim prefix="LIMIT" suffixOverrides=",">     ps：suffixOverrides=","意思是忽略,
           <if test="pageStart != null and pageStart != ''">
               #{pageStart},
           if>
           <if test="pageEnd != null and pageEnd != ''">
               #{pageEnd},
           if>
       trim>
   select>

代码比较全，复制时把所有ps去掉。
注意：sql语句里，不能加注释。 也不行

 <if test="taskKeyList != null and taskKeyList.size > 0">
    AND es.task_key in
        <foreach collection="taskKeyList" item="key" open="(" close=")" separator=",">
            #{key}
        </foreach>
 </if>
 PS: 单独拿这段解析。此时可以理解成当taskKeyList存在时，把其值一个一个添加到 AND es.task_key in()中。
 java代码如下：
	 String a = "AND es.task_key in(";
	 Steing b = ")";
	 String c = " ";
	 if( taskKeyList != null && taskKeyList.size() > 0){
	 	for(String key: taskKeyList){
	 		c += key; 
	 	}
	 }
	 return a+c+b ;

2.新增

 // 接口
 public boolean insertMessageReceive(MessageReceivedInfo messageReceivedInfo);

 
 <insert id="insertMessageReceive" parameterType="com.zhaoxi.tec.model.MessageReceivedInfo">
       insert into message_received_info
       <trim prefix="(" suffix=")" suffixOverrides=",">
           <if test="id != null">id,if>
           <if test="messageId != null">message_id,if>
           <if test="receivedUser != null">received_user,if>
           <if test="receivedTime != null">received_time,if>
       trim>
       <trim prefix="values (" suffix=")" suffixOverrides=",">
           <if test="id != null">#{id},if>
           <if test="messageId != null">#{messageId},if>
           <if test="receivedUser != null">#{receivedUser},if>
           <if test="receivedTime != null">#{receivedTime},if>
       trim>
  insert>

1. 一般增删改，返回值都是 boolean
2. parameterType=“全路径” ，可以不写
3. resultType=“java.lang.Integer” ，返回值为 String ,Integer ,List>等时，需要写

3.修改

 // 接口
 public boolean updateMessageReceive(MessageReceivedVo messageReceivedVo);

 <update id="updateMessageReceive" parameterType="com.zhaoxi.tec.model.MessageReceivedVo">
      UPDATE message_received_info
      <trim prefix="set" suffixOverrides=",">
          <if test="id!=null and id != ''">id=#{id},if>
          <if test="receivedTime!=null">received_time=#{receivedTime},if>
          <if test="receivedStatus!=null and receivedStatus != ''">received_status=#{receivedStatus},if>
      trim>
      <trim prefix="WHERE" prefixOverrides="AND">
          <if test="messageId != null and messageId != ''">
              message_id=#{messageId}
          if>
          <if test="id != null and id != ''">
              AND id=#{id}
          if>
          <if test="createTime != null ">      
              AND TO_DAYS(CREATE_TIME)= TO_DAYS(#{createTime})
           if>
      trim>
  update>

4. 删除

 // 接口
 public boolean deleteSunBusinessId(String perId,String deptId);

 <delete id="deleteSunBusinessId">
     DELETE FROM  evaluation_scheme_sun
      <trim prefix="WHERE" prefixOverrides="AND">
          <if test="perId != null and perId != ''">
              per_id=#{perId}
          if>
          <if test="deptId != null and deptId != ''">
              AND dept_id=#{deptId}
          if>
      trim>
  delete>