Mybatis的xml映射文件的常用标签汇总

一、*标签

sql – 可被其他语句引用的可重用语句块。

<sql > where valid = 1 </sql>

<select id = 'queryUser'>select * from user <include refid = 'valid'></include>

insert – 映射插入语句

<insert id = "saveUser">insert into User (id,name,sex) values (#{id},#{name},#{sex})<insert>

update – 映射更新语句

<update >
  update User set
    name = #{name},
    sex= #{sex}
  where id = #{id}
</update>

delete – 映射删除语句

<delete >
  delete from User where id = #{id}
</delete>

select – 映射查询语句

<select  parameterType="int" resultType="hashmap">
  SELECT * FROM UserWHERE ID = #{id}
</select>

二、动态sql标签

<select 
     resultType="User">
  SELECT * FROM User
  WHERE valid = 1
  <if test="name!= null">
    AND name like #{name}
  </if>
</select>

choose (when, otherwise)

<select 
     resultType="User">
  SELECT * FROM User WHERE age = 26
  <choose>
    <when test="name!= null">
      AND name like #{name}
    </when>
    <when test="sex!= null ">
      AND sex like #{sex}
    </when>
    <otherwise>
      AND valid = 1
    </otherwise>
  </choose>
</select>

trim (where, set)

//prefixOverrides 属性会忽略通过管道分隔的文本序列（注意此例中的空格也是必要的）。它的作用是移除所有指定在 prefixOverrides 属性中的内容，并且插入 prefix 属性中指定的内容。
<trim prefix="WHERE" prefixOverrides="AND |OR ">
  ...
</trim>

//set 元素会动态前置 SET 关键字，同时也会删掉无关的逗号
<trim prefix="SET" suffixOverrides=",">
  ...
</trim>

foreach

//collection="要遍历的集合" 
//item = "可以在元素体内使用的集合项"
//index = "索引"
//open = "开始字符串"
//separator = "分隔符"
//close = "结束字符串"
<select  resultType="User">
  SELECT *
  FROM User
  WHERE ID in
  <foreach item="item" index="index" collection="list"
      open="(" separator="," close=")">
        #{item}
  </foreach>
</select>

bind

//bind可以创建一个变量并将其绑定到上下文
<select  resultType="user">
  <bind name="pattern" value="'%' + _parameter.getTitle() + '%'" />
  SELECT * FROM User
  WHERE name LIKE #{pattern}
</select>

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Mybatis的xml映射文件的常用标签汇总

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