SQL Features That SQLite Does Not Implement

(This page was last modified on 2003/08/22 02:34:30 UTC)

Rather than try to list all the features of SQL92 that SQLite does support, it is much easier to list those that it does not. Unsupported features of SQL92 are shown below.

The order of this list gives some hint as to when a feature might be added to SQLite. Those features near the top of the list are likely to be added in the near future. There are no immediate plans to add features near the bottom of the list.

CHECK constraints   CHECK constraints are parsed but they are not enforced. NOT NULL and UNIQUE constraints are enforced, however.
Variable subqueries   Subqueries must be static. They are evaluated only once. They may not, therefore, refer to variables in the main query.
FOREIGN KEY constraints   FOREIGN KEY constraints are parsed but are not enforced.
Complete trigger support   There is some support for triggers but it is not complete. Missing subfeatures include FOR EACH STATEMENT triggers (currently all triggers must be FOR EACH ROW), INSTEAD OF triggers on tables (currently INSTEAD OF triggers are only allowed on views), and recursive triggers - triggers that trigger themselves.
ALTER TABLE   To change a table you have to delete it (saving its contents to a temporary table) and recreate it from scratch.
Nested transactions   The current implementation only allows a single active transaction.
The COUNT(DISTINCT X) function   You can accomplish the same thing using a subquery, like this:
  SELECT count(x) FROM (SELECT DISTINCT x FROM tbl);
RIGHT and FULL OUTER JOIN   LEFT OUTER JOIN is implemented, but not RIGHT OUTER JOIN or FULL OUTER JOIN.
Writing to VIEWs   VIEWs in SQLite are read-only. You may not execute a DELETE, INSERT, or UPDATE statement on a view. But you can create a trigger that fires on an attempt to DELETE, INSERT, or UPDATE a view and do what you need in the body of the trigger.
GRANT and REVOKE   Since SQLite reads and writes an ordinary disk file, the only access permissions that can be applied are the normal file access permissions of the underlying operating system. The GRANT and REVOKE commands commonly found on client/server RDBMSes are not implemented because they would be meaningless for an embedded database engine.

If you find other SQL92 features that SQLite does not support, please add them to the Wiki page at http://www.sqlite.org/cvstrac/wiki?p=Unsupported

Back to the SQLite Home Page