MySQL table data types
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This is from MySQL.com, column storage requirements

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Storage Requirements for Numeric Types
Column Type Storage Required
TINYINT 1 byte
SMALLINT 2 bytes
MEDIUMINT 3 bytes
INT, INTEGER 4 bytes
BIGINT 8 bytes
FLOAT(p) 4 bytes if 0 <= p <= 24, 8 bytes if 25 <= p <= 53
FLOAT 4 bytes
DOUBLE [PRECISION], item REAL 8 bytes
DECIMAL(M,D), NUMERIC(M,D) M+2 bytes if D > 0, M+1 bytes if D = 0 (D+2, if M < D)
BIT(M) approximately (M+7)/8 bytes

Storage Requirements for Date and Time Types
Column Type Storage Required
DATE 3 bytes
DATETIME 8 bytes
TIMESTAMP 4 bytes
TIME 3 bytes
YEAR 1 byte

Storage Requirements for String Types
Column Type Storage Required
CHAR(M) M bytes, 0 <= M <= 255
VARCHAR(M) L+1 bytes, where L <= M and 0 <= M <= 255
BINARY(M) M bytes, 0 <= M <= 255
VARBINARY(M) L+1 bytes, where L <= M and 0 <= M <= 255
TINYBLOB, TINYTEXT L+1 bytes, where L < 2^8
BLOB, TEXT L+2 bytes, where L < 2^16
MEDIUMBLOB, MEDIUMTEXT L+3 bytes, where L < 2^24
LONGBLOB, LONGTEXT L+4 bytes, where L < 2^32
ENUM('value1','value2',...) 1 or 2 bytes, depending on the number of enumeration values (65,535 values maximum)
SET('value1','value2',...) 1, 2, 3, 4, or 8 bytes, depending on the number of set members (64 members maximum)

VARCHAR and the BLOB and TEXT types are variable-length types. For each, the storage requirements depend on the actual length of column values (represented by L in the preceding table), rather than on the type's maximum possible size. For example, a VARCHAR(10) column can hold a string with a maximum length of 10. The actual storage required is the length of the string (L), plus 1 byte to record the length of the string. For the string 'abcd', L is 4 and the storage requirement is 5 bytes.

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