Grounded in the tsqldocs reference

Query Doctor

Paste the query that’s misbehaving and the exact error message (or leave the error blank if it runs but the result is wrong). Diagnose opens the AI assistant with an answer grounded in these docs.

Query Doctor

Your query

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Error message (optional)

Opens the AI panel with a fix grounded in the docs.

What you get back

  1. Root cause — the actual reason, not just “syntax error near…”.
  2. A corrected query — formatted, ready to paste into the playground.
  3. How to avoid it — the rule or habit that prevents the class of bug, linked to the relevant reference page.

Common ones it’s good at

Aggregate / GROUP BY mismatches

"column must appear in the GROUP BY clause"

A SELECT alias used in WHERE or HAVING

aliases aren’t visible yet at that stage

LEFT JOIN silently turned into an INNER JOIN

a WHERE filter on the right table

NOT IN returning nothing

the subquery has a NULL

Window function in WHERE

needs a subquery / CTE

Ambiguous column name

after a join, unqualified

Integer division flooring to 0

missing a numeric cast