Queries on BareSQL.com

Columns Missing From GROUP BY Work on SQLite and MariaDB and Fail on PostgreSQL and MySQL

Mon, 26 Oct 2026 00:00:00 +0000

SELECT customer_id, name, SUM(total) FROM orders GROUP BY customer_id is the kind of query that runs for years on SQLite or MariaDB. Point the same code at PostgreSQL or MySQL and it stops with an error, because name is neither grouped nor summed.

SELECT a, b FROM t GROUP BY a asks for one b per group without saying which. SQLite and MariaDB pick one (MariaDB’s default mode leaves out ONLY_FULL_GROUP_BY). PostgreSQL and MySQL stop with an error, unless the grouped column is the table’s primary key, which fixes every other column of that table.

Comparing a Boolean With 1 Works on MySQL and SQLite and Fails on PostgreSQL

Mon, 26 Oct 2026 00:00:00 +0000

WHERE active = 1 is the usual way to test a flag on MySQL, and SQLite and MariaDB read it the same way. Moved to PostgreSQL, the query stops with an error.

On SQLite, MySQL and MariaDB a boolean is the number 0 or 1, and TRUE is another way to write 1. PostgreSQL has a real boolean type with no automatic conversion from integers, so code written for MySQL that compares flags with 1 stops there.

COUNT DISTINCT With Two Columns Works on MySQL and Fails on PostgreSQL and SQLite

Mon, 26 Oct 2026 00:00:00 +0000

COUNT(DISTINCT customer_id, product_id) counts the distinct pairs on MySQL and MariaDB. SQLite and PostgreSQL take a single expression in COUNT(DISTINCT ...) and refuse it.

SQLite reports the wrong number of arguments and PostgreSQL a missing function.

DISTINCT ON Works on PostgreSQL Only

Mon, 26 Oct 2026 00:00:00 +0000

DISTINCT ON (customer_id) is a neat way to keep each customer’s latest order on PostgreSQL, and none of the other three engines has it.

SQLite, MySQL and MariaDB report a syntax error. Window functions say the same thing on all four (SQLite 3.25, MySQL 8.0 and MariaDB 10.2 and later).

FETCH FIRST ROWS ONLY Works on PostgreSQL and MariaDB and Fails on MySQL and SQLite

Mon, 26 Oct 2026 00:00:00 +0000

FETCH FIRST 10 ROWS ONLY is the standard way to ask for the top ten, and PostgreSQL and MariaDB accept it. SQLite and MySQL refuse the query.

MariaDB added FETCH FIRST in version 10.6. SQLite and MySQL know only LIMIT, and they refuse OFFSET n ROWS for the same reason.

FULL OUTER JOIN Works on PostgreSQL and SQLite and Fails on MySQL and MariaDB

Mon, 26 Oct 2026 00:00:00 +0000

Matching two lists, such as invoices and payments, to see what is missing on either side calls for a FULL OUTER JOIN. PostgreSQL and SQLite run it, and MySQL and MariaDB refuse it.

MySQL and MariaDB have LEFT and RIGHT joins only. SQLite added RIGHT and FULL joins in version 3.39.

LIMIT With a Comma Works on MySQL and SQLite and Fails on PostgreSQL

Mon, 26 Oct 2026 00:00:00 +0000

Paging code written for MySQL often says LIMIT 20, 10: skip 20 rows, return 10. SQLite and MariaDB read it the same way. PostgreSQL refuses it.

In LIMIT a, b the first number is the offset and the second the count, the reverse of the order in which LIMIT ... OFFSET reads.

MySQL and MariaDB Refuse LIMIT Inside an IN Subquery

Mon, 26 Oct 2026 00:00:00 +0000

Finding the customers behind the ten latest orders with WHERE id IN (SELECT customer_id FROM orders ORDER BY created_at DESC LIMIT 10) works on SQLite and PostgreSQL. MySQL and MariaDB refuse it.

Both report that this version doesn’t yet support 'LIMIT & IN/ALL/ANY/SOME subquery'. LIMIT is fine in a subquery used as a table and in one that returns a single value.

Only SQLite Lets WHERE Use a Name From the Select List

Mon, 26 Oct 2026 00:00:00 +0000

A query that names price * quantity as total in the select list and then filters on total in WHERE runs on SQLite. PostgreSQL, MySQL and MariaDB refuse it, since the table has no column named total.

WHERE is worked out before the select list, so in standard SQL the y of SELECT x * 2 AS y does not exist yet. SQLite looks it up anyway.

PostgreSQL Refuses Select List Names in HAVING

Mon, 26 Oct 2026 00:00:00 +0000

A report of repeat customers names its count of orders n in the select list and filters on that name in HAVING. SQLite, MySQL and MariaDB run it, and PostgreSQL refuses the query.

PostgreSQL looks up names in HAVING among the table’s columns only, so HAVING n > 1 fails when n is the name of COUNT(*).