MyBatis  Label usage summary

<select  resultType="">
   SELECT Id,Title FROM User
</select>

<resultMap  type="com.">
  <id column="stud_id" property="studId"  jdbcType="VARCHAR"/>
  <result column="user_name" property="name"  jdbcType="VARCHAR"/>
  <result column="email"  property="email"  jdbcType="VARCHAR" />
  <result column="phone"  property="phone"  jdbcType="VARCHAR" />
  <result column="status" property="status" jdbcType="INTEGER" />
  <result column="create_time" property="createTime" jdbcType="TIMESTAMP" />
</resultMap>
<select  resultMap="StudentResult" >
  SELECT * FROM STUDENTS
</select>

<resultMap type="Course" >
  <id column="course_id" property="courseId"/>
  <result column="name" property="name"/>
  <result column="description" property="description"/>
  <result column="start_date" property="startDate"/>
  <result column="end_date" property="endDate"/>
</resultMap>
<resultMap type="Tutor" >
  <id column="tutor_id" property="tutorId"/>
  <result column="tutor_name" property="name"/>
  <result column="email" property="email"/>
  <collection property="courses" resultMap="CourseResult"/>
</resultMap>
<select  parameterType="int" resultMap="TutorResult">
  SELECT T.TUTOR_ID,  AS TUTOR_NAME, EMAIL, C.COURSE_ID, , DESCRIPTION, START_DATE, END_DATE
  FROM TUTORS T LEFT OUTER JOIN ADDRESSES A ON T.ADDR_ID=A.ADDR_ID
  LEFT OUTER JOIN COURSES C ON T.TUTOR_ID=C.TUTOR_ID
  WHERE T.TUTOR_ID=#{tutorId}
</select>

<select  parameterType="hashmap" resultMap="CourseResult">
  SELECT * FROM COURSES
  <choose>
    <when test="searchBy == 'Tutor'">
      WHERE TUTOR_ID= #{tutorId}
    </when>
    <when test="searchBy == 'CourseName'">
      WHERE name like #{courseName}
    </when>
    <otherwise>
      WHERE TUTOR start_date  >= now()
    </otherwise>
  </choose>
</select>

<select  parameterType="hashmap" resultMap="CourseResult">
  SELECT * FROM COURSES
  <where>  
    <if test=" tutorId != null ">
      TUTOR_ID= #{tutorId}
    </if>
    <if test="courseName != null">
      AND name like #{courseName}
    </if>
    <if test="startDate != null">
      AND start_date  &gt;= #{startDate} <!--Greater than or equal to Start time-->    &lt;/if&gt;
    &lt;if test="endDate != null"&gt;
      AND end_date  &lt;= #{endDate} <!--less than or equal to end time-->    &lt;/if&gt;
  &lt;/where&gt;
&lt;/select&gt;

<select  parameterType="" resultType="">
select * from user
  <where>
    <!--
    collection:Specify the collection properties in the input object.There are three values ​​for this property：list,array,map，Set this value according to the type of the incoming set。
    item:Each traversal of generated objects
    index:The number of current iterations
    open:Splice string when starting traversal
    close:Strings that end up splicing
    separator:Traversing strings that need to be spliced ​​between objects
    select * from user where 1=1 and id in (1,2,3)
    -->
    <foreach collection="list" item="id" open="(" separator="," close=")">
     #{id}
    </foreach>
  </where>
</select>

<select  parameterType="" resultType="">
select * from user
  <where>
    <foreach collection="list" item="id" open="and (" close=")" separator="or">
       id=#{id}
    </foreach>
  </where>
</select>

<sql >
  id, question, answer 
</sql>
<select  parameterType="" resultMap="BaseResultMap">
  select 
  <include ref />
  from java
  where id = #{id,jdbcType=BIGINT}
</select>

<update>
  update user 
  <set>
    <if test="name != null and ()>0">name = #{name},</if>
    <if test="age != null and age .length()>0">age = #{age },</if>
  </set>
  where id = #{id}
</update>

<update>
    <foreach collection="list" item="item" index="index" separator=";">
        update user 
        <set>
            <if test="name != null and ()>0">name = #{name},</if>
            <if test="age != null and age .length()>0">age = #{age },</if>
        </set>
        <where>
            <if test="id != null and id != ''">
                AND id = #{id,jdbcType=VARCHAR}
            </if>
            <if test="userName != null and userName != ''">
                <bind name="bindUserName" value="'%' + userName + '%'" />
                AND UserName like #{bindUserName}
            </if> 
            <if test="status != null">
                AND Status = #{status,jdbcType=INTEGER}
            </if>
        </where>
    </foreach>
</update>

select * from user 
<trim prefix="WHERE" prefixoverride="AND |OR">
  <if test="name != null and ()>0"> AND name=#{name}</if>
  <if test="age != null and ()>0"> AND age=#{age}</if>
</trim> 
IfnameandageNone of the values ​​arenullIf it is printedSQLfor：select * from user where name = ‘xx' and age = ‘xx'
existwhereof后面是不存exist第一个andof，上面两个属性of意思如下：
prefix：Prefix
prefixoverride：Remove the first oneandOror

update user
<trim prefix="set" suffixoverride="," suffix=" where id = #{id} ">
  <if test="name != null and ()>0"> name=#{name} , </if>
  <if test="age!= null and ()>0"> age=#{age} ,  </if>
</trim>
IfnameandageNone of the values ​​arenullIf it is printedSQLfor：update user set name=‘xx' , age=‘xx' where id=‘x'
existage='xx'的后面不存exist逗号，And it's automatically addedset前缀andwheresuffix，The above three attributes are as follows，inprefixThe meaning is as above：
 suffixoverride：Remove the last comma（It can also be another mark，It's like the one in the prefix aboveandSame）
　 　suffix：suffix

<update  parameterType="" >
  update User
  set Status = 1,UpdateTime=(select GETDATE())
  <choose>
    <when test="idList != null and ==1">
      WHERE Id= #{id,jdbcType=VARCHAR}
    </when>
    <when test="idList != null and >1">
      WHERE Id in
      <foreach collection="idList" item="id" open="(" close=")" separator=",">
        <if test="id != null and id != '' ">
          #{id,jdbcType=VARCHAR}
        </if>
      </foreach>
    </when>
    <otherwise>
      WHERE 1=0
    </otherwise>
  </choose>
</update>