Thanks for the help this makes sense. The query works considerably faster. However I have one issue. Each part needs to run in order e.g.

For the 1st ID - if it was type 1 for example it needs to run

udf_TSC_qry_ExportBlockColumnParam1

and then

udf_TSC_qry_ExportBlockColumnParam2

So that in the output it is organised like:

OutputParam1 (ID 1)

OutputParam2 (ID 1)

OutputParam1 (ID 2)

OutputParam2 (ID 2)

and not

OutputParam1 (ID 1)

OutputParam1 (ID 2)

OutputParam2 (ID 1)

OutputParam2 (ID 2)

I hope this makes sense. Many thanks for your help, its almost there and runs in 1 second compared to 1 minute!

Oliver

SELECT *

FROM [dbo].[TSC_ExportedColumnIds] a

CROSS APPLY [dbo].[udf_TSC_qry_ExportBlockColumnParam1](a.ID) b

WHERE a.ColumnType = 1

UNION ALL

SELECT *

FROM [dbo].[TSC_ExportedColumnIds] a

CROSS APPLY [dbo].[udf_TSC_qry_ExportBlockColumnParam2](a.ID,4) b

WHERE a.ColumnType = 1

UNION ALL

SELECT *

FROM [dbo].[TSC_ExportedColumnIds] a

CROSS APPLY [dbo].[udf_TSC_qry_ExportSequenceColumnParam1](a.ID) b

WHERE a.ColumnType = 2

UNION ALL

SELECT *

FROM [dbo].[TSC_ExportedColumnIds] a

CROSS APPLY [dbo].[udf_TSC_qry_ExportSequenceColumnParam2](a.ID,4) b

WHERE a.ColumnType = 2

UNION ALL

SELECT A,B,C,D,E,F,G

FROM [dbo].[TSC_ExportedColumnIds] a

CROSS APPLY [dbo].[udf_TSC_qry_ExportEventColumnParam0](a.ID,4) b

WHERE a.ColumnType = 3;