Troubleshooting and Common Mistakes

15. Troubleshooting and Common Mistakes

15.1 Query Runs But No Results

Cause: WHERE clause is too restrictive or a filter value does not exist in the data.

Solution: Run a simpler query first (SELECT COUNT(*) FROM view_name) to confirm the view has data. Then add filters one at a time to isolate the problem.

15.2 Unexpected NULL Values

Cause: LEFT JOIN returns NULL when a matching row is not found in the right table.

Solution: Use INNER JOIN if you want to exclude unmatched rows. Use COALESCE(column, default_value) to fill NULLs with a placeholder.

15.3 Row Count Inflates

Cause: A join matches one left row to multiple right rows, duplicating the left row.

Solution: Identify the correct grain and use GROUP BY with aggregation. Or adjust the JOIN conditions to include more specific keys.

15.4 Permission Denied Errors

Cause: You do not have access to a view or the SQL Editor feature itself.

Solution: Contact your administrator to confirm your role includes SQL Editor access and access to the views you need.

15.5 Syntax Errors

Cause: Typo in SQL or unsupported SQL construct.

Solution: Review the error message, check for missing commas or mismatched parentheses, and consult the SQL Primer for correct syntax.

15.6 Performance: Slow Queries

Cause: Large dataset, expensive joins, or missing filters.

Solution: Add date filters or LIMIT to reduce result set. Start with a fact view and add dimensions selectively.