P0042 – Direct Query Against The BC Underlying Database

[Peter Jones]

I put this query on the BC Forums.

https://community.dynamics.com/forums/thread/details/?threadid=1f0d5fdf-68fe-ee11-a1fe-7c1e5219011a

Raul found this.

I know scenarios where cross or outer apply are good to use simply for row by row processing or sometimes performance, but I searched and here are the results that might answer the use of outer apply in those queries instead of left join.

Here are some reasons why OUTER APPLY might be used instead of LEFT JOIN:

1. Row-by-row processing: OUTER APPLY can be used to invoke a table-valued function for each row of the left table, which can be useful for complex calculations or transformations that need to be applied row-wise.
2. Derived tables with aggregates: It can be used to create derived tables that contain aggregated data without the need for a group by clause, which can simplify queries.
3. Correlated subqueries: OUTER APPLY can be used for correlated subqueries where the derived table needs to reference columns from the outer query.
4. Performance: In some cases, OUTER APPLY can offer better performance than a LEFT JOIN, especially when the function or derived table in the APPLY part is complex.
5. Flexibility: OUTER APPLY provides a level of flexibility that LEFT JOIN does not, particularly when dealing with dynamic sets of columns or when the joined table’s columns depend on the rows from the left table.

OUTER APPLY can be beneficial in scenarios where more complex data retrieval is necessary, such as when dealing with hierarchical data, dynamic columns, or when needing to perform operations unique to each row of the primary table

https://dba.stackexchange.com/questions/137546/comparing-left-join-and-outer-apply-doing-the-same-thing

https://dba.stackexchange.com/questions/75048/outer-apply-vs-left-join-performance

https://www.mssqltips.com/sqlservertip/1958/sql-server-cross-apply-and-outer-apply/

https://techcommunity.microsoft.com/t5/azure-database-support-blog/lesson-learned-468-understanding-and-resolving-the-quot-could/ba-p/4022046

https://www.mssqltips.com/sqlservertip/7491/prepare-sql-statement-spprepare-spexecute/

https://learn.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sp-prepare-transact-sql?view=sql-server-ver16

https://learn.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sp-prepexec-transact-sql?view=sql-server-ver16

• This topic was modified 11 months, 1 week ago by Peter Jones.

Best Regards
Peter Jones

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