Temporary Tables
Best Practices: SQL Temp Tables, CTEs, Table
Variables & Memory
Optimized Tables
When to use temporary tables, CTEs (Common Table Expressions), table variables, and memory-optimized tables in T-SQL scripts.
• Large dataset
• Multiple DML operation
• Need for indexes
CTEs
Table Variables
• Simplifying complex queries.
• Recursive queries
• One-time use.
• Use indexes to improve performance.
• Drop the table when it’s no longer needed to free up resources.
• Use local temp tables (#TempTable) for session-specific data and global temp tables (##TempTable) for data shared across sessions.
Script example from: mssqltips.com
• Use for simplifying complex queries and recursive operations.
• Avoid using CTEs for large datasets as they can impact performance.
• Ensure CTEs are used within the same query scope.
• TRY…CATCH Blocks: Use TRY...CATCH blocks to handle errors gracefully in your T-SQL scripts.
• Check for Existence: Before dropping temp tables, check if they exist using IF OBJECT_ID('tempdb..#TempTable') IS NOT NULL DROP TABLE #TempTable
• Handle Null Values: Ensure you handle null values appropriately to avoid runtime errors.
Error handling from: sqlservertutorial.net
• TRY…CATCH Blocks: Use TRY...CATCH blocks to handle errors gracefully in your TSQL scripts.
• Check for Existence: Before dropping temp tables, check if they exist using IF OBJECT_ID('tempdb..#TempTable') IS NOT NULL DROP TABLE #TempTable.
• Handle Null Values: Ensure you handle null values appropriately to avoid runtime errors.
• Small to medium datasets.
• Simple operations
• When memory usage is a concern.
Script example from: tutorialspoint.com
• Declare with DECLARE @TableVar TABLE
• Suitable for small to medium datasets.
• Avoid using for large datasets due to lack of statistics and indexing.
• Use for simple operations where memory usage is a concern.
Script Example from: sqlservertutorials.net
Error handling from: sqlservertutorial.net
• TRY…CATCH Blocks: Use TRY...CATCH blocks to handle errors gracefully in your TSQL scripts.
• Check for Existence: Before dropping temp tables, check if they exist using IF OBJECT_ID('tempdb..#TempTable') IS NOT NULL DROP TABLE #TempTable.
• Handle Null Values: Ensure you handle null values appropriately to avoid runtime errors.
Error handling from: sqlservertutorial.net
Feature When to Use
MemoryOptimized Tables
• Highperformance scenarios
• In-memory OLTP.
• Frequent access patterns
Best Practices
• Use MEMORY_OPTIMIZED = ON
• Ideal for high-performance scenarios and in-memory OLTP.
• Ensure proper indexing and monitor memory usage.
• Use for frequently accessed data to leverage in-memory performance benefits. Script Example from: SQL Server 2022
Error Handling
• TRY…CATCH Blocks: Use TRY...CATCH blocks to handle errors gracefully in your T-SQL scripts.
• Check for Existence: Before dropping temp tables, check if they exist using IF OBJECT_ID('tempdb..#TempTable') IS NOT NULL DROP TABLE #TempTable
• Handle Null Values: Ensure you handle null values appropriately to avoid runtime errors.
• Memory Allocation: For memory-optimized tables, handle memory allocation errors and monitor memory usage to prevent out-ofmemory issues.
Error handling from: sqlservertutorial.net