Integer Types (Exact Value)
MySQL supports the SQL standard integer types INTEGER
(or INT
) and SMALLINT
. As an extension to the standard, MySQL also supports the integer types TINYINT
, MEDIUMINT
, and BIGINT
. The following table shows the required storage and range for each integer type.
Table 11.1 Required Storage and Range for Integer Types Supported by MySQL
Type | Storage (Bytes) | Minimum Value Signed | Minimum Value Unsigned | Maximum Value Signed | Maximum Value Unsigned |
---|
TINYINT | 1 | -128 | 0 | 127 | 255 |
---|
SMALLINT | 2 | -32768 | 0 | 32767 | 65535 |
---|
MEDIUMINT | 3 | -8388608 | 0 | 8388607 | 16777215 |
---|
INT | 4 | -2147483648 | 0 | 2147483647 | 4294967295 |
---|
BIGINT | 8 | -263 | 0 | 263-1 | 264-1 |
---|
https://stackoverflow.com/questions/12839927/mysql-tinyint-2-vs-tinyint1-what-is-the-difference
It means display width
Whether you use tinyint(1) or tinyint(2), it does not make any difference.
I always use tinyint(1) and int(11), I used several mysql clients (navicat, sequel pro).
It does not mean anything AT ALL! I ran a test, all above clients or even the command-line client seems to ignore this.
But, display width is most important if you are using ZEROFILL
option, for example your table has following 2 columns:
A tinyint(2) zerofill
B tinyint(4) zerofill
For integer data types, M
indicates the maximum display width. The maximum display width is 255. Display width is unrelated to the range of values a type can store, as described in Section 11.1.6, “Numeric Type Attributes”.
For floating-point and fixed-point data types, M
is the total number of digits that can be stored.
As of MySQL 8.0.17, the display width attribute is deprecated for integer data types; you should expect support for it to be removed in a future version of MySQL.
If you specify ZEROFILL
for a numeric column, MySQL automatically adds the UNSIGNED
attribute to the column.
As of MySQL 8.0.17, the ZEROFILL
attribute is deprecated for numeric data types; you should expect support for it to be removed in a future version of MySQL. Consider using an alternative means of 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
.
BIT[(M
)]
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 |
+--------------------------------+
mysql> SELECT IF(1 = TRUE, 'true', 'false');
+-------------------------------+
| IF(1 = TRUE, 'true', 'false') |
+-------------------------------+
| true |
+-------------------------------+
mysql> SELECT IF(2 = TRUE, 'true', 'false');
+-------------------------------+
| IF(2 = TRUE, 'true', 'false') |
+-------------------------------+
| false |
+-------------------------------+
mysql> SELECT IF(2 = FALSE, 'true', 'false');
+--------------------------------+
| IF(2 = FALSE, 'true', 'false') |
+--------------------------------+
| false |
+--------------------------------+
The last two statements display the results shown because 2
is equal to neither 1
nor 0
.
SMALLINT[(M
)] [UNSIGNED] [ZEROFILL]
A small integer. The signed range is -32768
to 32767
. The unsigned range is 0
to 65535
.
MEDIUMINT[(M
)] [UNSIGNED] [ZEROFILL]
A medium-sized integer. The signed range is -8388608
to 8388607
. The unsigned range is 0
to 16777215
.
INT[(M
)] [UNSIGNED] [ZEROFILL]
A normal-size integer. The signed range is -2147483648
to 2147483647
. The unsigned range is 0
to 4294967295
.
INTEGER[(M
)] [UNSIGNED] [ZEROFILL]
This type is a synonym for INT
.
BIGINT[(M
)] [UNSIGNED] [ZEROFILL]
A large integer. The signed range is -9223372036854775808
to 9223372036854775807
. The unsigned range is 0
to 18446744073709551615
.
SERIAL
is an alias for BIGINT UNSIGNED NOT NULL AUTO_INCREMENT UNIQUE
.
Some things you should be aware of with respect to BIGINT
columns:
All arithmetic is done using signed BIGINT
or DOUBLE
values, so you should not use unsigned big integers larger than 9223372036854775807
(63 bits) except with bit functions! If you do that, some of the last digits in the result may be wrong because of rounding errors when converting a BIGINT
value to a DOUBLE
.
MySQL can handle BIGINT
in the following cases:
When using integers to store large unsigned values in a BIGINT
column.
In MIN(col_name
)
or MAX(col_name
)
, where col_name
refers to a BIGINT
column.
When using operators (+
, -
, *
, and so on) where both operands are integers.
You can always store an exact integer value in a BIGINT
column by storing it using a string. In this case, MySQL performs a string-to-number conversion that involves no intermediate double-precision representation.
The -
, +
, and *
operators use BIGINT
arithmetic when both operands are integer values. This means that if you multiply two big integers (or results from functions that return integers), you may get unexpected results when the result is larger than 9223372036854775807
.
DECIMAL[(M
[,D
])] [UNSIGNED] [ZEROFILL]
A packed “exact” fixed-point number. M
is the total number of digits (the precision) and D
is the number of digits after the decimal point (the scale). The decimal point and (for negative numbers) the -
sign are not counted in M
. If D
is 0, values have no decimal point or fractional part. The maximum number of digits (M
) for DECIMAL
is 65. The maximum number of supported decimals (D
) is 30. If D
is omitted, the default is 0. If M
is omitted, the default is 10. (There is also a limit on how long the text of DECIMAL
literals can be; see Section 12.25.3, “Expression Handling”.)
UNSIGNED
, if specified, disallows negative values. As of MySQL 8.0.17, the UNSIGNED
attribute is deprecated for columns of type 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.
All basic calculations (+, -, *, /
) with DECIMAL
columns are done with a precision of 65 digits.
DEC[(M
[,D
])] [UNSIGNED] [ZEROFILL]
, NUMERIC[(M
[,D
])] [UNSIGNED] [ZEROFILL]
, FIXED[(M
[,D
])] [UNSIGNED] [ZEROFILL]
These types are synonyms for DECIMAL
. The FIXED
synonym is available for compatibility with other database systems.
FLOAT[(M
,D
)] [UNSIGNED] [ZEROFILL]
A small (single-precision) floating-point number. Permissible values are -3.402823466E+38
to -1.175494351E-38
, 0
, and 1.175494351E-38
to 3.402823466E+38
. These are the theoretical limits, based on the IEEE standard. The actual range might be slightly smaller depending on your hardware or operating system.
M
is the total number of digits and D
is the number of digits following the decimal point. If M
and D
are omitted, values are stored to the limits permitted by the hardware. A single-precision floating-point number is accurate to approximately 7 decimal places.
FLOAT(M
,D
)
is a nonstandard MySQL extension. As of MySQL 8.0.17, this syntax is deprecated, and you should expect support for it to be removed in a future version of MySQL.
UNSIGNED
, if specified, disallows negative values. As of MySQL 8.0.17, the UNSIGNED
attribute is deprecated for columns of type FLOAT
(and any synonyms) and 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.
Using FLOAT
might give you some unexpected problems because all calculations in MySQL are done with double precision. See Section B.3.4.7, “Solving Problems with No Matching Rows”.
FLOAT(p
) [UNSIGNED] [ZEROFILL]
A floating-point number. p
represents the precision in bits, but MySQL uses this value only to determine whether to use FLOAT
or DOUBLE
for the resulting data type. If p
is from 0 to 24, the data type becomes FLOAT
with no M
or D
values. If p
is from 25 to 53, the data type becomes DOUBLE
with no M
or D
values. The range of the resulting column is the same as for the single-precision FLOAT
or double-precision DOUBLE
data types described earlier in this section.
UNSIGNED
, if specified, disallows negative values. As of MySQL 8.0.17, the UNSIGNED
attribute is deprecated for columns of type FLOAT
(and any synonyms) and 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.
FLOAT(p
)
syntax is provided for ODBC compatibility.
DOUBLE[(M
,D
)] [UNSIGNED] [ZEROFILL]
A normal-size (double-precision) floating-point number. Permissible values are -1.7976931348623157E+308
to -2.2250738585072014E-308
, 0
, and 2.2250738585072014E-308
to 1.7976931348623157E+308
. These are the theoretical limits, based on the IEEE standard. The actual range might be slightly smaller depending on your hardware or operating system.
M
is the total number of digits and D
is the number of digits following the decimal point. If M
and D
are omitted, values are stored to the limits permitted by the hardware. A double-precision floating-point number is accurate to approximately 15 decimal places.
DOUBLE(M
,D
)
is a nonstandard MySQL extension. As of MySQL 8.0.17, this syntax is deprecated and you should expect support for it to be removed in a future version of MySQL.
UNSIGNED
, if specified, disallows negative values. As of MySQL 8.0.17, the UNSIGNED
attribute is deprecated for columns of type DOUBLE
(and any synonyms) and 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.
DOUBLE PRECISION[(M
,D
)] [UNSIGNED] [ZEROFILL]
, REAL[(M
,D
)] [UNSIGNED] [ZEROFILL]
These types are synonyms for DOUBLE
. Exception: If the REAL_AS_FLOAT
SQL mode is enabled, REAL
is a synonym for FLOAT
rather than DOUBLE
.
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