Derived table must be aliased

Question

Accepted Answer

In standard SQL (and all major databases), every derived table - a subquery used in the FROM clause - must be given a name via AS alias. The fix: add an alias, e.g. ) AS totals at the end. Without it, the database cannot reference the result set and raises a syntax error. PostgreSQL, MySQL, and SQL Server all enforce this. The alias is then used to qualify columns if needed: totals.customer.