How to concatenating multiple rows of record into One record row in Cognos queries

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The link below from IBM demonstrated a solution to resolve this issue. However, it could be very slow duo to master detail relationship. in addition, it is not flexible at all. This article shows you another practical way to resolve this issue at Query level.

https://www.ibm.com/support/pages/how-combine-rows-list-report-single-row-comma-separated  How to combine rows in a list report into a single row that is comma separated.

Report output
Basic Data	Column1	Column2	Measure1	Rank4Column2	DistinctCount4Column2	Column21	Column22	Column23	Column24	Column25
	CTL 309306	IS-510977	10	2	2		IS-510977
	CTL 309316	IS-510979	10	2	2		IS-510979
	CTL 309316	IS-510980	10	1	2	IS-510980
	CTL 309306	IS-511129	10	1	2	IS-511129
Report Data	Column1	ConcatenationOfColumn2	Measure1
	CTL 309306	IS-511129;IS-510977	20
	CTL 309316	IS-510980;IS-510979	20
Report columns
Rank4Column2	rank  ( [Column2] for [Column1])
DistinctCount4Column2	count( distinct [Column2] for [Column1])
Column21	if ([Rank4Column2] = 1) THEN ([Column2]) ELSE (null)
Column22	if ([Rank4Column2] = 2) THEN ([Column2]) ELSE (null)
Column23	if ([Rank4Column2] = 3) THEN ([Column2]) ELSE (null)
Column24	if ([Rank4Column2] = 4) THEN ([Column2]) ELSE (null)
Column25	if ([Rank4Column2] = 5) THEN ([Column2]) ELSE (null)
ConcatenationOfColumn2 - CALCULATED	CASE WHEN maximum([BasicData].[DistinctCount4Column2]) = 1 THEN maximum([BasicData].[Column21]) WHEN maximum([BasicData].[DistinctCount4Column2]) = 2 THEN maximum([BasicData].[Column21]) || ';' || maximum([BasicData].[Column22]) WHEN maximum([BasicData].[DistinctCount4Column2]) = 3 THEN maximum([BasicData].[Column21]) || ';' || maximum([BasicData].[Column22]) || ';' || maximum([BasicData].[Column23]) WHEN maximum([BasicData].[DistinctCount4Column2]) = 4 THEN maximum([BasicData].[Column21]) || ';' || maximum([BasicData].[Column22]) || ';' || maximum([BasicData].[Column23]) || ';' || maximum([BasicData].[Column24]) WHEN maximum([BasicData].[DistinctCount4Column2]) = 5 THEN maximum([BasicData].[Column21]) || ';' || maximum([BasicData].[Column22]) || ';' || maximum([BasicData].[Column23]) || ';' || maximum([BasicData].[Column24]) || ';' || maximum([BasicData].[Column25]) END