Write, optimize, and debug T-SQL queries for Microsoft SQL Server. Covers CTEs, window functions, PIVOT, MERGE, APPLY operators, execution plan analysis, indexing strategies, and stored procedures. Use when working with SQL Server, T-SQL scripts, .sql files, stored procedures, query optimization, or database performance tuning.
Expert assistance for Microsoft SQL Server and T-SQL development.
When helping with T-SQL:
-- Non-SARGable (BAD)
WHERE YEAR(date_column) = 2024
-- SARGable (GOOD)
WHERE date_column >= '2024-01-01' AND date_column < '2025-01-01'
-- Implicit conversion (BAD)
WHERE nvarchar_column = @varchar_param
-- Type match (GOOD)
WHERE nvarchar_column = @nvarchar_param
BEGIN TRY
BEGIN TRANSACTION;
-- operations
COMMIT TRANSACTION;
END TRY
BEGIN CATCH
IF @@TRANCOUNT > 0 ROLLBACK TRANSACTION;
THROW;
END CATCH;
| Feature | Version |
|---|---|
| STRING_AGG, TRIM | 2017+ |
| JSON functions, STRING_SPLIT | 2016+ |
| GENERATE_SERIES, GREATEST/LEAST | 2022+ |