Get data with comma separated string from table using sql server

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DECLARE @StrClm varchar(50)

set @StrClm='1,2,3,4,5,6,7'

DECLARE @ListStr VARCHAR(MAX),@Ids varchar(50) = ''

set @Ids=','+@StrClm+','

SELECT @ListStr = COALESCE(@ListStr+',' ,'') + Description FROM mst_990Lookup where LookupFlag=36 and Charindex(','+cast(LookupCode as varchar(8000))+',', @Ids) > 0 --and Flag=1