# SQL language reference

Derby implements an SQL-92 core subset, as well as some SQL-99 features.

This section provides an overview of the current SQL language by describing the statements, built-in functions, data types, expressions, and special characters it contains.

- Capitalization and special characters
- SQL identifiers
- Statements
- SQL clauses
- SQL expressions
  Syntax for many statements and expressions includes the term Expression, or a term for a specific kind of expression such as TableSubquery. Expressions are allowed in these specified places within statements.
- JOIN operations
- SQL queries
- Built-in functions
- Built-in system functions
- Built-in system procedures
- SYSCS_DIAG diagnostic tables and functions
  Derby provides a set of system table expressions which you can use to obtain diagnostic information about the state of the database and about the database sessions.
- Data types