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<title>SQL Syntax</title>
<sect1>
<title>Key Words</title>
<para>
<acronym>SQL92</acronym> defines <firstterm>key words</firstterm>
for the language
which have specific meaning. Some key words are
<firstterm>reserved</firstterm>, which indicates that they are
restricted to appear in only certain contexts. Other key words are
<firstterm>not restricted</firstterm>, which indicates that in certain
contexts they
have a specific meaning but are not otherwise constrained.
<para>
<productname>Postgres</productname> implements an extended subset of the
<acronym>SQL92</acronym> and <acronym>SQL3</acronym> languages. Some language
elements are not as restricted in this implementation as is
called for in the language standards, in part due
to the extensibility features of <productname>Postgres</productname>.
<para>
Information on <acronym>SQL92</acronym> and <acronym>SQL3</acronym> key words
is derived from <xref linkend="DATE97" endterm="DATE97">.
</para>
<sect2>
<title>Reserved Key Words</title>
<acronym>SQL92</acronym> and <acronym>SQL3</acronym> have
<firstterm>reserved key words</firstterm> which are not allowed
as identifiers and not allowed in any usage other than as fundamental
tokens in <acronym>SQL</acronym> statements.
<productname>Postgres</productname> has additional key words
which have similar restrictions. In particular, these key words
are not allowed as column or table names, though in some cases
they are allowed to be column labels (i.e. in AS clauses).
<tip>
<para>
Any string can be specified as an identifier if surrounded by
double quotes (<quote>like this!</quote>). Some care is required since
such an identifier will be case sensitive
and will retain embedded whitespace other special characters.</para>
</tip>
<para>
The following are <productname>Postgres</productname>
reserved words which are neither <acronym>SQL92</acronym>
nor <acronym>SQL3</acronym> reserved words. These are allowed
to be present as column labels, but not as identifiers:
<programlisting>
ABORT ANALYZE
BINARY
CLUSTER CONSTRAINT COPY
DO
EXPLAIN EXTEND
LISTEN LOAD LOCK
MOVE
NEW NONE NOTIFY
RESET
SETOF SHOW
UNLISTEN UNTIL
VACUUM VERBOSE
</programlisting>
The following are <productname>Postgres</productname>
reserved words which are also <acronym>SQL92</acronym>
or <acronym>SQL3</acronym> reserved words, and which
are allowed to be present as column labels, but not as identifiers:
<programlisting>
CASE COALESCE CROSS CURRENT
ELSE END
FALSE FOREIGN
GROUP
ORDER
POSITION PRECISION
TABLE THEN TRANSACTION TRUE
WHEN
</programlisting>
The following are <productname>Postgres</productname>
reserved words which are also <acronym>SQL92</acronym>
or <acronym>SQL3</acronym> reserved words:
<programlisting>
ADD ALL ALTER AND ANY AS ASC
BEGIN BETWEEN BOTH BY
CASCADE CAST CHAR CHARACTER CHECK CLOSE
COLLATE COLUMN COMMIT CONSTRAINT
CREATE CURRENT_DATE CURRENT_TIME
CURRENT_TIMESTAMP CURRENT_USER CURSOR
DECIMAL DECLARE DEFAULT DELETE DESC DISTINCT DROP
FETCH FLOAT FOR FROM FULL
GRANT
HAVING
IN INNER INSERT INTERVAL INTO IS
JOIN
LEADING LEFT LIKE LOCAL
NAMES NATIONAL NATURAL NCHAR NO NOT NULL NUMERIC
ON OR OUTER
PARTIAL PRIMARY PRIVILEGES PROCEDURE PUBLIC
REFERENCES REVOKE RIGHT ROLLBACK
SELECT SET SUBSTRING
UNION UNIQUE UPDATE USER USING
VALUES VARCHAR VARYING VIEW
WHERE WITH WORK
</programlisting>
The following are <acronym>SQL92</acronym> reserved key words which
are not <productname>Postgres</productname> reserved key words, but which
if used as function names are always translated into the function
<function>length</function>:
<programlisting>
CHAR_LENGTH CHARACTER_LENGTH
</programlisting>
The following are <acronym>SQL92</acronym> or <acronym>SQL3</acronym>
reserved key words which
are not <productname>Postgres</productname> reserved key words, but
if used as type names are always translated into an alternate, native type:
<programlisting>
BOOLEAN DOUBLE FLOAT INT INTEGER INTERVAL REAL SMALLINT
</programlisting>
<para>
The following are either <acronym>SQL92</acronym>
or <acronym>SQL3</acronym> reserved key words
which are not key words in <productname>Postgres</productname>.
These have no proscribed usage in <productname>Postgres</productname>
at the time of writing (v6.4) but may become reserved key words in the
future:
<note>
<para>
Some of these key words represent functions in <acronym>SQL92</acronym>.
These functions are defined in <productname>Postgres</productname>,
but the parser does not consider the names to be key words and they are allowed
in other contexts.
</note>
<programlisting>
ALLOCATE ARE ASSERTION AT AUTHORIZATION AVG
BIT BIT_LENGTH
CASCADED CATALOG COLLATION CONNECT CONNECTION
CONSTRAINTS CONTINUE CONVERT CORRESPONDING COUNT
DATE DEALLOCATE DEC DESCRIBE DESCRIPTOR DIAGNOSTICS DISCONNECT DOMAIN
END-EXEC ESCAPE EXCEPT EXCEPTION EXEC EXTERNAL
FIRST FOUND
GET GLOBAL GO GOTO
IDENTITY IMMEDIATE INDICATOR INITIALLY INPUT INTERSECT ISOLATION
LAST LEVEL LOWER
MAX MIN MODULE
OCTET_LENGTH OPEN OUTPUT OVERLAPS
PREPARE PRESERVE
RESTRICT ROWS
SCHEMA SECTION SESSION SESSION_USER SIZE SOME
SQL SQLCODE SQLERROR SQLSTATE SUM SYSTEM_USER
TEMPORARY TRANSLATE TRANSLATION
UNKNOWN UPPER USAGE
VALUE
</programlisting>
<sect2>
<title>Non-reserved Keywords</title>
<acronym>SQL92</acronym> and <acronym>SQL3</acronym> have
<firstterm>non-reserved keywords</firstterm> which have
a proscribed meaning in the language but which are also allowed
as identifiers.
<productname>Postgres</productname> has additional keywords
which allow similar unrestricted usage.
In particular, these keywords
are allowed as column or table names.
<para>
The following are <productname>Postgres</productname>
non-reserved key words which are neither <acronym>SQL92</acronym>
nor <acronym>SQL3</acronym> non-reserved key words:
<programlisting>
AFTER AGGREGATE
BACKWARD BEFORE
CACHE CREATEDB CREATEUSER CYCLE
DATABASE DELIMITERS
EACH ENCODING
FORWARD FUNCTION
HANDLER
INCREMENT INDEX INHERITS INSENSITIVE INSTEAD ISNULL
LANCOMPILER LOCATION
MAXVALUE MINVALUE
NOCREATEDB NOCREATEUSER NOTHING NOTNULL
OIDS OPERATOR
PASSWORD PROCEDURAL
RECIPE RENAME RETURNS ROW RULE
SEQUENCE SERIAL START STATEMENT STDIN STDOUT
TRUSTED
VALID VERSION
</programlisting>
<para>
The following are <productname>Postgres</productname>
non-reserved key words which are <acronym>SQL92</acronym>
or <acronym>SQL3</acronym> reserved key words:
<programlisting>
ABSOLUTE ACTION
DAY
HOUR
INSENSITIVE
KEY
LANGUAGE
MATCH MINUTE MONTH
NEXT
OF ONLY OPTION
PRIOR PRIVILEGES
READ RELATIVE
SCROLL SECOND
TIME TIMESTAMP TIMEZONE_HOUR TIMEZONE_MINUTE TRIGGER
YEAR
ZONE
</programlisting>
<para>
The following are <productname>Postgres</productname>
non-reserved key words which are also either <acronym>SQL92</acronym>
or <acronym>SQL3</acronym> non-reserved key words:
<programlisting>
TYPE
</programlisting>
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
<para>
The following are either <acronym>SQL92</acronym>
or <acronym>SQL3</acronym> non-reserved key words which are not
key words of any kind in <productname>Postgres</productname>:
<programlisting>
ADA
C CATALOG_NAME CHARACTER_SET_CATALOG CHARACTER_SET_NAME
CHARACTER_SET_SCHEMA CLASS_ORIGIN COBOL COLLATION_CATALOG
COLLATION_NAME COLLATION_SCHEMA COLUMN_NAME
COMMAND_FUNCTION COMMITTED CONDITION_NUMBER
CONNECTION_NAME CONSTRAINT_CATALOG CONSTRAINT_NAME
CONSTRAINT_SCHEMA CURSOR_NAME
DATA DATE_TIME_INTERVAL_CODE DATE_TIME_INTERVAL_PRECISION
DYNAMIC_FUNCTION
FORTRAN
LENGTH
MESSAGE_LENGTH MESSAGE_OCTET_LENGTH MORE MUMPS
NAME NULLABLE NUMBER
PAD PASCAL PLI
REPEATABLE RETURNED_LENGTH RETURNED_OCTET_LENGTH
RETURNED_SQLSTATE ROW_COUNT
SCALE SCHEMA_NAME SERIALIZABLE SERVER_NAME SPACE
SUBCLASS_ORIGIN
TABLE_NAME
UNCOMMITTED UNNAMED
</programlisting>
</para>
</sect2>
</sect1>
</chapter>
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