sql-queries-error-handling-and-debugging

name	sql-queries-error-handling-and-debugging
description	Sub-skill of sql-queries: Error Handling and Debugging.
version	1.0.0
category	data-analytics
type	reference
scripts_exempt	true

Error Handling and Debugging

Error Handling and Debugging

When a query fails:

1. Syntax errors: Check for dialect-specific syntax (e.g., ILIKE not available in BigQuery, SAFE_DIVIDE only in BigQuery)
2. Column not found: Verify column names against schema -- check for typos, case sensitivity (PostgreSQL is case-sensitive for quoted identifiers)
3. Type mismatches: Cast explicitly when comparing different types (CAST(col AS DATE), col::DATE)
4. Division by zero: Use NULLIF(denominator, 0) or dialect-specific safe division
5. Ambiguous columns: Always qualify column names with table alias in JOINs
6. Group by errors: All non-aggregated columns must be in GROUP BY (except in BigQuery which allows grouping by alias)