9.3 Reserved Words

Certain words such as SELECT, DELETE, or BIGINT are reserved and require special treatment for use as identifiers such as table and column names. This may also be true for the names of built-in functions.

Reserved words are permitted as identifiers if you quote them as described in Section 9.2, “Schema Object Names”:

mysql> CREATE TABLE interval (begin INT, end INT);
ERROR 1064 (42000): You have an error in your SQL syntax ...
near 'interval (begin INT, end INT)'

mysql> CREATE TABLE `interval` (begin INT, end INT);
Query OK, 0 rows affected (0.01 sec)

Exception: A word that follows a period in a qualified name must be an identifier, so it need not be quoted even if it is reserved:

mysql> CREATE TABLE mydb.interval (begin INT, end INT);
Query OK, 0 rows affected (0.01 sec)

Names of built-in functions are permitted as identifiers but may require care to be used as such. For example, COUNT is acceptable as a column name. However, by default, no whitespace is permitted in function invocations between the function name and the following ( character. This requirement enables the parser to distinguish whether the name is used in a function call or in nonfunction context. For further detail on recognition of function names, see Section 9.2.3, “Function Name Parsing and Resolution”.

The words in the following table are explicitly reserved in MySQL 5.0. At some point, you might upgrade to a higher version, so it is a good idea to have a look at future reserved words, too. You can find these in the manuals that cover higher versions of MySQL. Most of the words in the table are forbidden by standard SQL as column or table names (for example, GROUP). A few are reserved because MySQL needs them and uses a yacc parser. A reserved word can be used as an identifier if you quote it.

For a more detailed list of reserved words, including differences between versions, see Reserved Words in MySQL 5.0.

Table 9.2 Reserved Words in MySQL 5.0.96

ADD ALL ALTER
ANALYZE AND AS
ASC ASENSITIVE BEFORE
BETWEEN BIGINT BINARY
BLOB BOTH BY
CALL CASCADE CASE
CHANGE CHAR CHARACTER
CHECK COLLATE COLUMN
CONDITION CONSTRAINT CONTINUE
CONVERT CREATE CROSS
CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP
CURRENT_USER CURSOR DATABASE
DATABASES DAY_HOUR DAY_MICROSECOND
DAY_MINUTE DAY_SECOND DEC
DECIMAL DECLARE DEFAULT
DELAYED DELETE DESC
DESCRIBE DETERMINISTIC DISTINCT
DISTINCTROW DIV DOUBLE
DROP DUAL EACH
ELSE ELSEIF ENCLOSED
ESCAPED EXISTS EXIT
EXPLAIN FALSE FETCH
FLOAT FLOAT4 FLOAT8
FOR FORCE FOREIGN
FROM FULLTEXT GRANT
GROUP HAVING HIGH_PRIORITY
HOUR_MICROSECOND HOUR_MINUTE HOUR_SECOND
IF IGNORE IN
INDEX INFILE INNER
INOUT INSENSITIVE INSERT
INT INT1 INT2
INT3 INT4 INT8
INTEGER INTERVAL INTO
IS ITERATE JOIN
KEY KEYS KILL
LEADING LEAVE LEFT
LIKE LIMIT LINES
LOAD LOCALTIME LOCALTIMESTAMP
LOCK LONG LONGBLOB
LONGTEXT LOOP LOW_PRIORITY
MATCH MEDIUMBLOB MEDIUMINT
MEDIUMTEXT MIDDLEINT MINUTE_MICROSECOND
MINUTE_SECOND MOD MODIFIES
NATURAL NOT NO_WRITE_TO_BINLOG
NULL NUMERIC ON
OPTIMIZE OPTION OPTIONALLY
OR ORDER OUT
OUTER OUTFILE PRECISION
PRIMARY PROCEDURE PURGE
READ READS REAL
REFERENCES REGEXP RELEASE
RENAME REPEAT REPLACE
REQUIRE RESTRICT RETURN
REVOKE RIGHT RLIKE
SCHEMA SCHEMAS SECOND_MICROSECOND
SELECT SENSITIVE SEPARATOR
SET SHOW SMALLINT
SONAME SPATIAL SPECIFIC
SQL SQLEXCEPTION SQLSTATE
SQLWARNING SQL_BIG_RESULT SQL_CALC_FOUND_ROWS
SQL_SMALL_RESULT SSL STARTING
STRAIGHT_JOIN TABLE TERMINATED
THEN TINYBLOB TINYINT
TINYTEXT TO TRAILING
TRIGGER TRUE UNDO
UNION UNIQUE UNLOCK
UNSIGNED UPDATE USAGE
USE USING UTC_DATE
UTC_TIME UTC_TIMESTAMP VALUES
VARBINARY VARCHAR VARCHARACTER
VARYING WHEN WHERE
WHILE WITH WRITE
XOR YEAR_MONTH ZEROFILL

Table 9.3 New Reserved Words in MySQL 5.0

ASENSITIVE CALL CONDITION
CONNECTION CONTINUE CURSOR
DECLARE DETERMINISTIC EACH
ELSEIF EXIT FETCH
GOTO INOUT INSENSITIVE
ITERATE LABEL LEAVE
LOOP MODIFIES OUT
READS RELEASE REPEAT
RETURN SCHEMA SCHEMAS
SENSITIVE SPECIFIC SQL
SQLEXCEPTION SQLSTATE SQLWARNING
TRIGGER UNDO UPGRADE
WHILE

MySQL permits some keywords to be used as unquoted identifiers because many people previously used them. Examples are those in the following list: