Table Variables In SQL Server: These tables behave very much like other variables in their scoping rules. They are created when they are declared and are dropped when they go out of scope. They cannot be explicitly dropped. Like with temp tables, table variables also reside in TempDB. They are also generally accessed only from memory, unless the server is under memory pressure or the amount of data in the table is large.
Table variables can have a primary key, but no indexes can be created on them. They don’t have any statistics maintained on the columns. This makes table variables less optimal for large numbers of rows, as the optimizer has no way of … Read the rest