15 Common SQL Errors (and How to Fix Them)

SQL is a powerful language for querying and managing data—but even experienced developers run into frustrating errors. Fortunately, most SQL errors are easy to diagnose once you understand their causes.

In this guide, we’ll walk through the most common SQL mistakes, show you how to fix them, and help you avoid them in the future. If you're just getting started, this will make your SQL debugging process much smoother.

Try fixing these interactively using the Galaxy SQL Editor.

1. Syntax Error near '...'

Error:

Syntax error near 'FROM'


Cause: A missing keyword, comma, or quotation mark.

Fix: Double-check your SQL syntax. Make sure all clauses are correctly ordered and spelled.

-- Bad:
SELECT name email FROM users;
-- Good:
SELECT name, email FROM users;


2. Unknown Column

Error:

Unknown column 'emial' in 'field list'


Cause: Typos in column names.

Fix: Use DESCRIBE table_name; or check your schema. Confirm the column exists and is spelled correctly.

3. Column Ambiguity in Joins

Error:

Column 'id' in field list is ambiguous


Cause: Multiple joined tables have a column with the same name.

Fix: Use table aliases or fully qualified names.

SELECT users.id, orders.id FROM users JOIN orders ON users.id = orders.user_id;


Learn more in our SQL JOINs guide.

4. Missing WHERE Clause in UPDATE or DELETE

Problem: No error, but unexpectedly updates/deletes all rows.

Fix: Always include a WHERE clause unless you're sure you want to affect every row.

-- Danger!
DELETE FROM users;
-- Better:
DELETE FROM users WHERE id = 123;


5. Invalid Date Format

Error:

Incorrect datetime value: '13/31/2022'


Cause: Wrong date format for your database (often expects YYYY-MM-DD).

Fix: Format the date correctly.

SELECT * FROM orders WHERE created_at = '2022-12-31';


6. Divide by Zero

Error:

ERROR: division by zero


Fix: Use a CASE or NULLIF() to protect against division by zero.

SELECT amount / NULLIF(quantity, 0) FROM sales;


7. Using = NULL Instead of IS NULL

Problem: No results returned when they should be.

Fix: Use IS NULL instead of = NULL.

-- Incorrect
SELECT * FROM users WHERE email = NULL;
-- Correct
SELECT * FROM users WHERE email IS NULL;


Read our full guide on SQL NULL values.

8. Using Aggregate Functions Without GROUP BY

Error:

Not a GROUP BY expression


Cause: You're selecting a non-aggregated column without grouping it.

Fix: Add a GROUP BY clause.

SELECT department, COUNT(*) FROM employees GROUP BY department;


Need a refresher? Check our SQL functions guide.

9. Mismatched Columns in INSERT

Error:

Column count doesn't match value count


Fix: Make sure the number of columns matches the number of values.

-- Incorrect
INSERT INTO users (name, email) VALUES ('Alice');
-- Correct
INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com');


10. Case Sensitivity in Identifiers

Some SQL dialects are case-sensitive with column or table names.

Fix: Always use consistent casing or quote your identifiers.

SELECT "UserName" FROM Users;


11. ORDER BY Without LIMIT (and Vice Versa)

Issue: Unexpected sort order or inconsistent pagination results.

Fix: Use ORDER BY with LIMIT for reliable pagination.

SELECT * FROM users ORDER BY created_at DESC LIMIT 10;


More on this in our LIMIT and OFFSET guide.

12. Using SELECT * in Joins

Problem: Duplicate or confusing columns.

Fix: Specify only the columns you need.

SELECT users.name, orders.total FROM users JOIN orders ON users.id = orders.user_id;


13. Incorrect Quoting of Strings vs. Identifiers

Error:

Unknown column 'email@example.com'


Fix: Strings go in single quotes; identifiers don’t.

SELECT * FROM users WHERE email = 'email@example.com';


14. Incorrect Use of OFFSET Without ORDER BY

Problem: Inconsistent results on paginated queries.

Fix: Always pair OFFSET with ORDER BY to guarantee consistent order.

SELECT * FROM posts ORDER BY created_at DESC LIMIT 10 OFFSET 20;


15. Typos in Table Names or SQL Keywords

Error:

ERROR: relation 'usres' does not exist


Fix: Check spelling carefully, especially for table names and SQL keywords like SELECT, FROM, WHERE, GROUP BY.

Final Thoughts

SQL errors are frustrating, but they’re also fantastic learning opportunities. The more you troubleshoot, the more confident you’ll become writing accurate, efficient queries.

The next time you see an error, revisit this list—or practice directly in the Galaxy SQL Editor, where you can safely test and refine your queries.

Continue learning: