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producing the effect of this attribute. For example, applications could use the LPAD()  function to zero-pad numbers up to the desired width, or they could store the formatted numbers in CHAR  columns. 

Numeric data types that permit the UNSIGNED  attribute also permit SIGNED . However, these data types are signed by default, so the SIGNED  attribute has no effect. 

As of MySQL 8.0.17, the UNSIGNED  attribute is deprecated for columns of type FLOAT , DOUBLE , and DECIMAL  (and any synonyms); you should expect support for it to be removed in a future version of MySQL. Consider using a simple CHECK  constraint instead for such columns. 

SERIAL  is an alias for BIGINT UNSIGNED NOT NULL AUTO_INCREMENT UNIQUE . 

SERIAL DEFAULT VALUE  in the definition of an integer column is an alias for NOT NULL AUTO_INCREMENT UNIQUE . 

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• BIT[( M )] 

## Warning 

When you use subtraction between integer values where one is of type UNSIGNED , the result is unsigned unless the NO_UNSIGNED_SUBTRACTION  SQL mode is enabled. See Section 12.11, “Cast Functions and Operators” . 

A bit-value type. M  indicates the number of bits per value, from 1 to 64. The default is 1 if M  is omitted. 

• TINYINT[( M )] [UNSIGNED] [ZEROFILL] 

A very small integer. The signed range is -128  to 127 . The unsigned range is 0  to 255 . 

• BOOL , BOOLEAN 

These types are synonyms for TINYINT(1) . A value of zero is considered false. Nonzero values are considered true: 

mysql> SELECT IF(0, ’true’, ’false’); +------------------------+ | IF(0, ’true’, ’false’) | +------------------------+ | false | +------------------------+ 

mysql> SELECT IF(1, ’true’, ’false’); +------------------------+ | IF(1, ’true’, ’false’) | +------------------------+ | true | +------------------------+ 

mysql> SELECT IF(2, ’true’, ’false’); +------------------------+ | IF(2, ’true’, ’false’) | +------------------------+ | true | +------------------------+ 

However, the values TRUE  and FALSE  are merely aliases for 1  and 0 , respectively, as shown here: 

mysql> SELECT IF(0 = FALSE, ’true’, ’false’); +--------------------------------+ | IF(0 = FALSE, ’true’, ’false’) | +--------------------------------+ | true | +--------------------------------+ 

