Enterprise T-SQL
Best Practices.

A curated catalogue of 41 T-SQL rules covering performance, security, maintainability, and safety — built from years of enterprise Data Engineering experience.

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Performance

Best Practices

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Showing 41 of 41 rules

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Enterprise T-SQLBest Practices.

Avoid SELECT *

Avoid NOLOCK hint

Replace cursors with set-based operations

Avoid functions on columns in WHERE

Add missing indexes on join/filter columns

Align data types to prevent implicit conversions

Avoid leading wildcard in LIKE

Always add a WHERE clause to SELECT/UPDATE/DELETE

Prefer inline TVFs over scalar UDFs

Validate UNION ALL usage

Prefer CREATE TABLE + INSERT over SELECT INTO #temp

Manage TempDB impact from #temp tables

Evaluate table variables for small data sets

Prefer CTEs over subqueries in FROM

Materialise subqueries in JOINs using CTEs

Prefer EXISTS/NOT EXISTS over subqueries in WHERE

Prefer EXISTS/JOINs over IN with subqueries

Validate EXISTS simplification with JOIN

LIKE with leading wildcard — consider Full-Text

Parameterise hardcoded values in filters

Align parameter types with column definitions

Avoid Linked Servers — prefer replication or ETL

Specify PATH and schema in OPENJSON

Replace WHILE + DML with set-based operations

Consolidate sequential UPDATEs on the same table

Always use schema prefix

Add SET NOCOUNT ON to all procedures

Avoid the sp_ prefix for stored procedures

Terminate statements with semicolons

Add TRY/CATCH with transaction handling

Remove SELECTs without effect

Procedure missing SET NOCOUNT ON

Use sp_executesql instead of EXEC(@sql)

Avoid OPENQUERY / OPENDATASOURCE / OPENROWSET

Avoid cross-database DML

Parameterise all user inputs

Apply least-privilege permissions

Avoid GOTO — use structured control flow

Migrate TEXT/NTEXT/IMAGE to modern types

Resolve unresolved or ambiguous dependencies

DELETE/UPDATE without WHERE detected

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Enterprise T-SQL
Best Practices.