# SQL queries

- query
  A query creates a virtual table based on existing tables or constants built into tables.
- scalarSubquery
  A scalarSubquery, sometimes called an expression subquery, is a subquery that evaluates to a single row with a single column.
- tableSubquery
  A tableSubquery is a subquery that returns multiple rows.

Parent topic: SQL language reference
Related concepts
SQL identifiers
Statements
Built-in system functions
Built-in system procedures
Data types
Related reference
Capitalization and special characters
SQL clauses
SQL expressions
JOIN operations
Built-in functions
SYSCS_DIAG diagnostic tables and functions