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CTE

sql server DBA 999

SQL Server Tsql CTE Common Table Expressions

CTE: CTE’s (SQL Common Table Expression ) are more like temporary views than anything else. When you look at the execution plan, you’ll see that they are substituted/inlined into the query but not materialized and stored anywhere. With the exception of recursion, they’re more to make queries simpler to write than faster to run.

CTE: CTE’s are more like temporary views than anything else. When you look at the execution plan, you’ll see that they are substituted/inlined into the query but not materialized and stored anywhere. With the exception of recursion, they’re more to make queries simpler to write than faster to run.

Example below

Say Query is below which … Read the rest

sql server DBA 999

CTE vs Temp Table vs Temp variables

Temp tables: they are just like any normal tables except that they are created in the TempDB database. They persist until dropped, or until the connection that created them disappears. They are visible in the procedure that created them and any procedures that it calls. Just like normal tables and have primary keys, constraints, indexes and column statistics which are kept for the table which makes query execution really fast in most cases.

Temp tables have space assigned to them in the TempDB database and are generally accessed only from memory, unless the server is under memory pressure or the amount of data in the table is large.

Table Variables: These tables behave very much … Read the rest