What are the key differences between temporary tables and table variables?
What are the key differences between temporary tables and table variables?
481
30-Apr-2025
Updated on 03-May-2025
Khushi Singh
03-May-20251. Declaration and Syntax -
Temporary Table: You create it with `CREATE TABLE #TempTable or SELECT INTO #TempTable.
Table Variable:You declare it with DECLARE @TableVar TABLE(...).
2. Scope and Visibility -
Temporary Table: It lasts for your session or until you drop it, and you can see it across stored procedures and batches in that session. -
Table Variable: Its use is limited to the batch or procedure where it’s declared, so you can’t access it outside of that.
3. Storage-
Temporary Table: This is stored in the tempdb database, and you can index it and perform analysis using statistics.
Table Variable: This is also stored in tempdb but doesn't have automatic stats and indexing unless you set them up yourself.
4. Performance -
Temporary Table:Works better for larger data and complex tasks since it supports indexing and stats.
Table Variable: It does well with small datasets, but performance can drop with larger ones because the query optimizer assumes there's just one row unless you use the RECOMPILE hint.
5. Transactions and Rollback -
Temporary Table: It works fully within transactions, so you can roll back changes.
Table Variable: It has limited support for transactions, so changes might not roll back like you expect.
6. Constraints and Indexes -
Temporary Table:You can add primary keys, unique constraints, and non-clustered indexes to it.
Table Variable: You can define primary keys and unique constraints when you create it, but options for indexing are limited.