mybatis中的choose標籤的使用

首先看原來代碼

<insert id="insert" parameterType="Class" >
    <selectKey resultType="java.lang.Long" keyProperty="id" order="AFTER" >
      SELECT LAST_INSERT_ID()
    </selectKey>
    insert into allocate_order (allocate_code, created_at, create_user,
      updated_at, update_user, dr, 
      ts, version)
    values (#{code,jdbcType=VARCHAR}, #{createdAt,jdbcType=TIMESTAMP}, #{createUser,jdbcType=VARCHAR}, 
      #{updatedAt,jdbcType=TIMESTAMP}, #{updateUser,jdbcType=VARCHAR}, #{dr,jdbcType=CHAR}, 
      #{ts,jdbcType=TIMESTAMP}, #{version,jdbcType=INTEGER})
  </insert>

在字段肯定，可是在沒有值的時候，咱們須要給他們添加默認值，更改後代碼爲

<insert id="insert" parameterType="Class" >
    <selectKey resultType="java.lang.Long" keyProperty="id" order="AFTER" >
      SELECT LAST_INSERT_ID()
    </selectKey>
    insert into allocate_order (dr,allocate_code,create_user,update_user,version) values (
      <choose>
          <when test="dr != null and dr != '' ">
              #{dr,jdbcType=CHAR},
          </when>
          <otherwise>
              '1',
          </otherwise>
      </choose>
      <choose>
          <when test="code != null and code != '' ">
              #{code,jdbcType=VARCHAR},
          </when>
          <otherwise>
              '',
          </otherwise>
      </choose>
      <choose>
          <when test="createUser != null and createUser != '' ">
              #{createUser,jdbcType=VARCHAR},
          </when>
          <otherwise>
              '',
          </otherwise>
      </choose>
      <choose>
          <when test="updateUser != null and updateUser != '' ">
              #{updateUser,jdbcType=VARCHAR},
          </when>
          <otherwise>
              '',
          </otherwise>
      </choose>
      <choose>
          <when test="version != null and version != '' ">
              #{version,jdbcType=INTEGER}
          </when>
          <otherwise>
              1
          </otherwise>
      </choose>)
  </insert>

這裏是用了choose標籤when標籤和otherwise標籤，結合使用能夠針對不一樣狀況做出反應

下面貼一個比較典型的操做 一個choose標籤下能夠有多個狀況，相似在判斷的時候的if ,else if,else這些

<select id="findUserInfoByOneParam" parameterType="Map" resultMap="UserInfoResult">
		select * from userinfo 
		<choose>
			<when test="searchBy=='department'">
				where department=#{department}
			</when>
			<when test="searchBy=='position'">
				where position=#{position}
			</when>
			<otherwise>
				where gender=#{gender}
			</otherwise>
			
		</choose>
		<if test="gender!=null">
			and gender=#{gender}
	<span style="white-space:pre">	</span></if>
</select>