Setting the SQL Mode

The Most Important SQL Modes

Full List of SQL Modes

Strict SQL Mode

Combination SQL Modes

ANSI

This mode changes syntax and behavior to conform more closely to standard SQL. It is one of the special combination modes listed at the end of this section.

STRICT_TRANS_TABLES

If a value could not be inserted as given into a transactional table, abort the statement. For a nontransactional table, abort the statement if the value occurs in a single-row statement or the first row of a multiple-row statement. More details are given later in this section.

TRADITIONAL

Make MySQL behave like a “traditional” SQL database system. A simple description of this mode is “give an error instead of a warning” when inserting an incorrect value into a column. It is one of the special combination modes listed at the end of this section.

ALLOW_INVALID_DATES

Do not perform full checking of dates. Check only that the month is in the range from 1 to 12 and the day is in the range from 1 to 31. This is very convenient for Web applications where you obtain year, month, and day in three different fields and you want to store exactly what the user inserted (without date validation). This mode applies to DATE and DATETIME columns. It does not apply TIMESTAMP columns, which always require a valid date.

The server requires that month and day values be legal, and not merely in the range 1 to 12 and 1 to 31, respectively. With strict mode disabled, invalid dates such as '2004-04-31' are converted to '0000-00-00' and a warning is generated. With strict mode enabled, invalid dates generate an error. To permit such dates, enable ALLOW_INVALID_DATES.

ANSI_QUOTES

Treat “"” as an identifier quote character (like the “`” quote character) and not as a string quote character. You can still use “`” to quote identifiers with this mode enabled. With ANSI_QUOTES enabled, you cannot use double quotation marks to quote literal strings, because it is interpreted as an identifier.

ERROR_FOR_DIVISION_BY_ZERO

The ERROR_FOR_DIVISION_BY_ZERO mode affects handling of division by zero, which includes MOD(N,0). For data-change operations (INSERT, UPDATE), its effect also depends on whether strict SQL mode is enabled.

For SELECT, division by zero returns NULL. Enabling ERROR_FOR_DIVISION_BY_ZERO causes a warning to be produced as well, regardless of whether strict mode is enabled.

As of MySQL 5.6.17, ERROR_FOR_DIVISION_BY_ZERO is deprecated and setting the sql_mode value to include it generates a warning. In MySQL 5.7, this mode does nothing. Instead, its effect is included in the effects of strict mode.

HIGH_NOT_PRECEDENCE

The precedence of the NOT operator is such that expressions such as NOT a BETWEEN b AND c are parsed as NOT (a BETWEEN b AND c). In some older versions of MySQL, the expression was parsed as (NOT a) BETWEEN b AND c. The old higher-precedence behavior can be obtained by enabling the HIGH_NOT_PRECEDENCE SQL mode.

mysql> SET sql_mode = '';
mysql> SELECT NOT 1 BETWEEN -5 AND 5;
        -> 0
mysql> SET sql_mode = 'HIGH_NOT_PRECEDENCE';
mysql> SELECT NOT 1 BETWEEN -5 AND 5;
        -> 1

IGNORE_SPACE

Permit spaces between a function name and the “(” character. This causes built-in function names to be treated as reserved words. As a result, identifiers that are the same as function names must be quoted as described in Section 9.2, “Schema Object Names”. For example, because there is a COUNT() function, the use of count as a table name in the following statement causes an error:

mysql> CREATE TABLE count (i INT);
ERROR 1064 (42000): You have an error in your SQL syntax

The table name should be quoted:

mysql> CREATE TABLE `count` (i INT);
Query OK, 0 rows affected (0.00 sec)

The IGNORE_SPACE SQL mode applies to built-in functions, not to user-defined functions or stored functions. It is always permissible to have spaces after a UDF or stored function name, regardless of whether IGNORE_SPACE is enabled.

For further discussion of IGNORE_SPACE, see Section 9.2.4, “Function Name Parsing and Resolution”.

NO_AUTO_CREATE_USER

Prevent the GRANT statement from automatically creating new users if it would otherwise do so, unless authentication information is specified. The statement must specify a nonempty password using IDENTIFIED BY or an authentication plugin using IDENTIFIED WITH.

NO_AUTO_VALUE_ON_ZERO

NO_AUTO_VALUE_ON_ZERO affects handling of AUTO_INCREMENT columns. Normally, you generate the next sequence number for the column by inserting either NULL or 0 into it. NO_AUTO_VALUE_ON_ZERO suppresses this behavior for 0 so that only NULL generates the next sequence number.

This mode can be useful if 0 has been stored in a table's AUTO_INCREMENT column. (Storing 0 is not a recommended practice, by the way.) For example, if you dump the table with mysqldump and then reload it, MySQL normally generates new sequence numbers when it encounters the 0 values, resulting in a table with contents different from the one that was dumped. Enabling NO_AUTO_VALUE_ON_ZERO before reloading the dump file solves this problem. mysqldump now automatically includes in its output a statement that enables NO_AUTO_VALUE_ON_ZERO, to avoid this problem.

NO_BACKSLASH_ESCAPES

Disable the use of the backslash character (“\”) as an escape character within strings. With this mode enabled, backslash becomes an ordinary character like any other.

NO_DIR_IN_CREATE

When creating a table, ignore all INDEX DIRECTORY and DATA DIRECTORY directives. This option is useful on slave replication servers.

NO_ENGINE_SUBSTITUTION

Control automatic substitution of the default storage engine when a statement such as CREATE TABLE or ALTER TABLE specifies a storage engine that is disabled or not compiled in.

Because storage engines can be pluggable at runtime, unavailable engines are treated the same way:

With NO_ENGINE_SUBSTITUTION disabled, for CREATE TABLE the default engine is used and a warning occurs if the desired engine is unavailable. For ALTER TABLE, a warning occurs and the table is not altered.

With NO_ENGINE_SUBSTITUTION enabled, an error occurs and the table is not created or altered if the desired engine is unavailable.

NO_FIELD_OPTIONS

Do not print MySQL-specific column options in the output of SHOW CREATE TABLE. This mode is used by mysqldump in portability mode.

NO_KEY_OPTIONS

Do not print MySQL-specific index options in the output of SHOW CREATE TABLE. This mode is used by mysqldump in portability mode.

NO_TABLE_OPTIONS

Do not print MySQL-specific table options (such as ENGINE) in the output of SHOW CREATE TABLE. This mode is used by mysqldump in portability mode.

NO_UNSIGNED_SUBTRACTION

By default, subtraction between integer operands produces an UNSIGNED result if any operand isUNSIGNED. When NO_UNSIGNED_SUBTRACTION is enabled, the subtraction result is signed, even if any operand is unsigned. For example, compare the type of column c2 in table t1 with that of column c2 in table t2:

mysql> SET sql_mode='';
mysql> CREATE TABLE test (c1 BIGINT UNSIGNED NOT NULL);
mysql> CREATE TABLE t1 SELECT c1 - 1 AS c2 FROM test;
mysql> DESCRIBE t1;
+-------+---------------------+------+-----+---------+-------+
| Field | Type                | Null | Key | Default | Extra |
+-------+---------------------+------+-----+---------+-------+
| c2    | bigint(21) unsigned |      |     | 0       |       |
+-------+---------------------+------+-----+---------+-------+

mysql> SET sql_mode='NO_UNSIGNED_SUBTRACTION';
mysql> CREATE TABLE t2 SELECT c1 - 1 AS c2 FROM test;
mysql> DESCRIBE t2;
+-------+------------+------+-----+---------+-------+
| Field | Type       | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| c2    | bigint(21) |      |     | 0       |       |
+-------+------------+------+-----+---------+-------+

This means that BIGINT UNSIGNED is not 100% usable in all contexts. See Section 12.10, “Cast Functions and Operators”.

mysql> SET sql_mode = '';
mysql> SELECT CAST(0 AS UNSIGNED) - 1;
+-------------------------+
| CAST(0 AS UNSIGNED) - 1 |
+-------------------------+
|    18446744073709551615 |
+-------------------------+

mysql> SET sql_mode = 'NO_UNSIGNED_SUBTRACTION';
mysql> SELECT CAST(0 AS UNSIGNED) - 1;
+-------------------------+
| CAST(0 AS UNSIGNED) - 1 |
+-------------------------+
|                      -1 |
+-------------------------+

NO_ZERO_DATE

The NO_ZERO_DATE mode affects whether the server permits '0000-00-00' as a valid date. Its effect also depends on whether strict SQL mode is enabled.

As of MySQL 5.6.17, NO_ZERO_DATE is deprecated and setting the sql_mode value to include it generates a warning. In MySQL 5.7, this mode does nothing. Instead, its effect is included in the effects of strict mode.

NO_ZERO_IN_DATE

The NO_ZERO_IN_DATE mode affects whether the server permits dates in which the year part is nonzero but the month or day part is 0. (This mode affects dates such as '2010-00-01' or '2010-01-00', but not '0000-00-00'. To control whether the server permits '0000-00-00', use the NO_ZERO_DATE mode.) The effect of NO_ZERO_IN_DATE also depends on whether strict SQL mode is enabled.

As of MySQL 5.6.17, NO_ZERO_IN_DATE is deprecated and setting the sql_mode value to include it generates a warning. In MySQL 5.7, this mode does nothing. Instead, its effect is included in the effects of strict mode.

ONLY_FULL_GROUP_BY

Reject queries for which the select list, HAVING condition, or (as of MySQL 5.6.5) ORDER list refer to nonaggregated columns that are not named in the GROUP BY clause.

The following queries are invalid with ONLY_FULL_GROUP_BY enabled. The first is invalid because the nonaggregated address column in the select list is not named in the GROUP BY clause, and the second because max_age in the HAVING clause is not named in the GROUP BY clause:

mysql> SELECT name, address, MAX(age) FROM t GROUP BY name;
ERROR 1055 (42000): 't.address' isn't in GROUP BY

mysql> SELECT name, MAX(age) AS max_age FROM t GROUP BY name
    -> HAVING max_age < 30;
Empty set (0.00 sec)
ERROR 1463 (42000): Non-grouping field 'max_age' is used in HAVING clause

In the second example, the query could be rewritten to use HAVING MAX(age) instead, so that the reference is to a column named in an aggregate function. (max_age fails because it is an aggregate function.)

If a query has aggregate functions and no GROUP BY clause, it cannot have nonaggregated columns in the select list or ORDER BY list with ONLY_FULL_GROUP_BY enabled:

mysql> SELECT name, MAX(age) FROM t;
ERROR 1140 (42000): Mixing of GROUP columns (MIN(),MAX(),COUNT(),...)
with no GROUP columns is illegal if there is no GROUP BY clause

For additional discussion, see Section 12.19.3, “MySQL Handling of GROUP BY”.

PAD_CHAR_TO_FULL_LENGTH

By default, trailing spaces are trimmed from CHAR column values on retrieval. If PAD_CHAR_TO_FULL_LENGTH is enabled, trimming does not occur and retrieved CHAR values are padded to their full length. This mode does not apply to VARCHAR columns, for which trailing spaces are retained on retrieval.

mysql> CREATE TABLE t1 (c1 CHAR(10));
Query OK, 0 rows affected (0.37 sec)

mysql> INSERT INTO t1 (c1) VALUES('xy');
Query OK, 1 row affected (0.01 sec)

mysql> SET sql_mode = '';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT c1, CHAR_LENGTH(c1) FROM t1;
+------+-----------------+
| c1   | CHAR_LENGTH(c1) |
+------+-----------------+
| xy   |               2 |
+------+-----------------+
1 row in set (0.00 sec)

mysql> SET sql_mode = 'PAD_CHAR_TO_FULL_LENGTH';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT c1, CHAR_LENGTH(c1) FROM t1;
+------------+-----------------+
| c1         | CHAR_LENGTH(c1) |
+------------+-----------------+
| xy         |              10 |
+------------+-----------------+
1 row in set (0.00 sec)

PIPES_AS_CONCAT

Treat || as a string concatenation operator (same as CONCAT()) rather than as a synonym for OR.

REAL_AS_FLOAT

Treat REAL as a synonym for FLOAT. By default, MySQL treats REAL as a synonym for DOUBLE.

STRICT_ALL_TABLES

Enable strict mode for all storage engines. Invalid data values are rejected. Additional details follow.

STRICT_TRANS_TABLES

Enable strict mode for transactional storage engines, and when possible for nontransactional storage engines. Additional details follow.

For transactional tables, an error occurs for invalid or missing values in a data-change statement when either STRICT_ALL_TABLES or STRICT_TRANS_TABLES is enabled. The statement is aborted and rolled back.

For nontransactional tables, the behavior is the same for either mode if the bad value occurs in the first row to be inserted or updated: The statement is aborted and the table remains unchanged. If the statement inserts or modifies multiple rows and the bad value occurs in the second or later row, the result depends on which strict mode is enabled:

ANSI

Equivalent to REAL_AS_FLOAT, PIPES_AS_CONCAT, ANSI_QUOTES, IGNORE_SPACE.

ANSI mode also causes the server to return an error for queries where a set function S with an outer reference S(outer_ref) cannot be aggregated in the outer query against which the outer reference has been resolved. This is such a query:

SELECT * FROM t1 WHERE t1.a IN (SELECT MAX(t1.b) FROM t2 WHERE ...);

Here, MAX(t1.b) cannot aggregated in the outer query because it appears in the WHERE clause of that query. Standard SQL requires an error in this situation. If ANSI mode is not enabled, the server treats S(outer_ref) in such queries the same way that it would interpret S(const).

See Section 1.8, “MySQL Standards Compliance”.

DB2

Equivalent to PIPES_AS_CONCAT, ANSI_QUOTES, IGNORE_SPACE, NO_KEY_OPTIONS, NO_TABLE_OPTIONS, NO_FIELD_OPTIONS.

MAXDB

Equivalent to PIPES_AS_CONCAT, ANSI_QUOTES, IGNORE_SPACE, NO_KEY_OPTIONS, NO_TABLE_OPTIONS, NO_FIELD_OPTIONS, NO_AUTO_CREATE_USER.

MSSQL

Equivalent to PIPES_AS_CONCAT, ANSI_QUOTES, IGNORE_SPACE, NO_KEY_OPTIONS, NO_TABLE_OPTIONS, NO_FIELD_OPTIONS.

MYSQL323

Equivalent to NO_FIELD_OPTIONS, HIGH_NOT_PRECEDENCE.

MYSQL40

Equivalent to NO_FIELD_OPTIONS, HIGH_NOT_PRECEDENCE.

ORACLE

Equivalent to PIPES_AS_CONCAT, ANSI_QUOTES, IGNORE_SPACE, NO_KEY_OPTIONS, NO_TABLE_OPTIONS, NO_FIELD_OPTIONS, NO_AUTO_CREATE_USER.

POSTGRESQL

Equivalent to PIPES_AS_CONCAT, ANSI_QUOTES, IGNORE_SPACE, NO_KEY_OPTIONS, NO_TABLE_OPTIONS, NO_FIELD_OPTIONS.

TRADITIONAL

Equivalent to STRICT_TRANS_TABLES, STRICT_ALL_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, NO_AUTO_CREATE_USER, and NO_ENGINE_SUBSTITUTION.