Comments on: SQL command when inserting M:N association with identity columns in the underlying table http://blog.cincura.net/231230-sql-command-when-inserting-mn-association-with-identity-columns-in-the-underlying-table/ Taking something that can't be done, and then doing it. Tue, 07 Sep 2010 14:25:21 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: cincura.net http://blog.cincura.net/231230-sql-command-when-inserting-mn-association-with-identity-columns-in-the-underlying-table/#comment-2462 cincura.net Fri, 19 Feb 2010 08:10:57 +0000 http://blog.cincura.net/?p=231230#comment-2462 I know what's there. But for a first sight without semicolons it was "interesting". :) I know what’s there. But for a first sight without semicolons it was “interesting”. :)

]]> By: Craig Stuntz http://blog.cincura.net/231230-sql-command-when-inserting-mn-association-with-identity-columns-in-the-underlying-table/#comment-2460 Craig Stuntz Thu, 18 Feb 2010 14:51:33 +0000 http://blog.cincura.net/?p=231230#comment-2460 There are three statements here. The first, which is line 1 only, declares a table-valued variable. Table valued variables are sort of like temp tables, but they are scoped only for the current batch. The second, which is lines 2 through 4, does the INSERT. The third, lines 5-7, returns the identity values. The basic problem is that you cannot use SCOPE_IDENTITY() to retrieve the identity values, since there is more than one. But the EF needs to know the values for both columns, so that it can set the entity keys correctly. There are three statements here.

The first, which is line 1 only, declares a table-valued variable. Table valued variables are sort of like temp tables, but they are scoped only for the current batch.

The second, which is lines 2 through 4, does the INSERT.

The third, lines 5-7, returns the identity values.

The basic problem is that you cannot use SCOPE_IDENTITY() to retrieve the identity values, since there is more than one. But the EF needs to know the values for both columns, so that it can set the entity keys correctly.

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