mysql find_in_set function use

SELECT
		  BRANCH_CODE,
		  BRANCH_NAME,
		  iae.FACE_AMT,
		  iae.SPEC,
		  iae.BEGIN_NO,
		  iae.END_NO,
		  (iae.PASS_BEN*iae.SPEC) AS RESERVE_COUNT,
		  iae.CODE,
		  iae.TOTAL_AMT,
		  DATE_FORMAT(SIGN_TIME, '%Y-%m-%d %H:%i:%S') AS ALLOT_TIME
		FROM
		  invoice_applys ia
where 1=1
<if test = 'paramMap.BRANCH_CODE != null and paramMap.BRANCH_CODE != ""'>
			and find_in_set(ia.BRANCH_CODE, ${paramMap.BRANCH_CODE}) > 0
			</if>
<!--The incoming BRANCH_CODE should be added with '', such as: '005,009,118'find_in_set function returns a number greater than 0 as long as ia.BRANCH_CODE exists in ${paramMap.BRANCH_CODE}-->