Temporary Tables And Table Variables In SQL 基本常识 1. 局部临时表(#开头)只对当前连接有效,当前连接断开时自动删除 2. 全局临时表(##开头)对其它连接也有效,在当前连接和其他访问过它的连接都断开时自动删除 3. 临时表就像普通表一样,它可以做索引等等 4. 临时表存在 tempdb database, 表变量存在 memory...
Temporary Tables And Table Variables In SQL 基本常识 1. 局部临时表(#开头)只对当前连接有效,当前连接断开时自动删除 2. 全局临时表(##开头)对其它连接也有效,在当前连接和其他访问过它的连接都断开时自动删除 3. 临时表就像普通表一样,它可以做索引等等 4. 临时表存在 tempdb database, 表变量存在 memory...
SQL Server creates and maintains statistics for temporary tables, which lead to better cardinality estimation and optimal execution plan generation. Table variables have no statistics, which can result in poor cardinality estimation and non-optimal execu
Following are scenarios where temp table/variable are not cached: 1. select into #t 2. alter table #t 3. create index on #t 4. Global temp tables (##t) 5. Local temp tables on adhoc level (nest level 0) 6. table variables are also...
Temporary Tables and Table Variables 全局临时表:##T1 局部临时表:#T1 表变量:@T1 临时表vs表变量:可见性,持久性,性能(具体见下表) 临时表有统计信息可以支持优化 表变量不需要重新编译 Table 2-4: Comparison Summary
15. Unlike a #temp table, you cannot drop a table variable when it is no longer necessary—you just need to let it go out of scope. 16. You can’t build the table variable inside dynamic SQL. This is because the rest of the script knows nothing about the temporary objects created wi...
其实在SQL Server中存在两种临时表:局部临时表和全局临时表,局部临时表(Local temp table)以#前缀来标识,并且只能被创建它的连接所使用.全局临时表(Global temp table)以##前缀来进行标识,并且可以和其它连接所共享.局部临时表局部临时表不能够被其它连接所共享的原因其实是在SQL Server 2000中自动为局部临时表的表...
D. Scenario: Table variable can be MEMORY_OPTIMIZED=ON Show 4 more Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance If you use temporary tables, table variables, or table-valued parameters, consider conversions of them to leverage memory-optimized tables and table variables...
Temp tables may be a better solution in this case. For queries that join the table variable with other tables, use the RECOMPILE hint, which causes the optimizer to use the correct cardinality for the table variable. table variables aren't supported in the SQL Server optimizer's cost-based...
Fixes an issue that triggers an access violation when you run a stored procedure that uses a cursor on a table variable in SQL Server.