selectKey 컬럼 여러개, 여러번

별칭을 #{별칭명}에 쓰면 됨

<insert id="insertUser">

		<selectKey resultType="hashmap" keyProperty="maxDeptCode,maxPosCode,maxAuthCode" order="BEFORE">
 		 SELECT 
	        (SELECT MAX(DETAIL_CODE) FROM tb WHERE CMMN_CODE = 'mem_dept_code') AS maxDeptCode,
	        (SELECT MAX(DETAIL_CODE) FROM tb WHERE CMMN_CODE = 'mem_pos_code') AS maxPosCode,
	        (SELECT MAX(DETAIL_CODE) FROM tb WHERE CMMN_CODE = 'mem_auth_code') AS maxAuthCode
	        FROM DUAL
        </selectKey> 

	INSERT INTO member
	(
		mem_id
		, mem_dept_code
		, mem_pos_code
		, mem_auth_code

	)
	VALUES
	(
		#{memId}
		<choose>
			<when test="memDeptCode == 0">
				, #{maxDeptCode}
			</when>
			<otherwise>
				, #{memDeptCode}
			</otherwise>
		</choose>
		<choose>
			<when test="memPosCode == 0">
				, #{maxPosCode}
			</when>
			<otherwise>
				, #{memPosCode}
			</otherwise>
		</choose>
		<choose>
			<when test="memAuthCode == 0">
				, #{maxAuthCode}
			</when>
			<otherwise>
				, #{memAuthCode}
			</otherwise>
		</choose>
	)

</insert>

처음에는 selectKey를 여러번 넣었으나 그건 안되는거같아서 쿼리를 하나로 조합해서 하니 되었다.