sql server - SQL left outer join with nested select optimisation -


I ask SQL Server 2012.

I have left external connectors on a big result set, which looks like the following:

  Add data left otters (Member ID, Mid (date) Members from the members of the table of the member) data on t. Member ID = T. Member ID  

Where the data is already a large query (thousands of rows come back).

My question is, is this nested selection query evaluated for the member ID present in "Data" only? It seems that the sproc is quite slow down quite a lot, is there another standard way to do this?

No, should this be expected?

If you want the first line for something, do this: seqnum as

and then use:

  where seqnum = 1  

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