declare variable sql w3schools code example
Example 1: sql data types
CHAR(size)
Fixed length string which can contain letters, numbers and special
characters. The size parameter sets the maximum string length, from
0 – 255 with a default of 1.
VARCHAR(size) Variable length string similar to CHAR(), but with a maximum string
length range from 0 to 65535.
BINARY(size) Similar to CHAR() but stores binary byte strings.
VARBINARY(size) Similar to VARCHAR() but for binary byte strings.
TINYBLOB Holds Binary Large Objects (BLOBs) with a max length of 255 bytes.
TINYTEXT Holds a string with a maximum length of 255 characters. Use
VARCHAR() instead, as it’s fetched much faster.
TEXT(size) Holds a string with a maximum length of 65535 bytes. Again, better to
use VARCHAR().
BLOB(size) Holds Binary Large Objects (BLOBs) with a max length of 65535
bytes.
MEDIUMTEXT Holds a string with a maximum length of 16,777,215 characters.
MEDIUMBLOB Holds Binary Large Objects (BLOBs) with a max length of 16,777,215
bytes.
LONGTEXT Holds a string with a maximum length of 4,294,967,295 characters.
LONGBLOB Holds Binary Large Objects (BLOBs) with a max length of
4,294,967,295 bytes.
ENUM(a, b, c,
etc…)
A string object that only has one value, which is chosen from a list of
values which you define, up to a maximum of 65535 values. If a value
is added which isn’t on this list, it’s replaced with a blank value instead.
Think of ENUM being similar to HTML radio boxes in this regard.
CREATE TABLE tshirts (color ENUM(‘red’, ‘green’,
‘blue’, ‘yellow’, ‘purple’));
SET(a, b, c, etc…)
A string object that can have 0 or more values, which is chosen from a
list of values which you define, up to a maximum of 64 values. Think of
SET being similar to HTML checkboxes in this regard.
Example 2: sql What type is that value?
SELECT TYPEOF(value);