SQL Data Types

sql-data-type

SQL Data Types for MySQL, SQL Server, and MS Access

The data type of a column defines what value the column can hold: integer, character, money, date and time, binary, and so on.

SQL Data Types

Every segment in a database table is needed to have a name and a data type.

A SQL engineer must choose what type of data that will be put away inside every segment while making a table. The data type is a rule for SQL to comprehend what type of data is normal within every section, and it additionally distinguishes how SQL will collaborate with the put away data.

MySQL Data Types (Version 8.0)

In MySQL there are three main data types: string, numeric, and date and time.

String data types:

Data typeDescription
CHAR(size)A FIXED length string (can contain letters, numbers, and special characters). The size parameter specifies the column length in characters – can be from 0 to 255. Default is 1
VARCHAR(size)A VARIABLE length string (can contain letters, numbers, and special characters). The size parameter specifies the maximum column length in characters – can be from 0 to 65535
BINARY(size)Equal to CHAR(), but stores binary byte strings. The size parameter specifies the column length in bytes. Default is 1
VARBINARY(size)Equal to VARCHAR(), but stores binary byte strings. The size parameter specifies the maximum column length in bytes.
TINYBLOBFor BLOBs (Binary Large OBjects). Max length: 255 bytes
TINYTEXTHolds a string with a maximum length of 255 characters
TEXT(size)Holds a string with a maximum length of 65,535 bytes
BLOB(size)For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data
MEDIUMTEXTHolds a string with a maximum length of 16,777,215 characters
MEDIUMBLOBFor BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data
LONGTEXTHolds a string with a maximum length of 4,294,967,295 characters
LONGBLOBFor BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data
ENUM(val1, val2, val3, …)A string object that can have only one value, chosen from a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted. The values are sorted in the order you enter them
SET(val1, val2, val3, …)A string object that can have 0 or more values, chosen from a list of possible values. You can list up to 64 values in a SET list

Numeric data types:

Data typeDescription
BIT(size)A bit-value type. The number of bits per value is specified in size. The size parameter can hold a value from 1 to 64. The default value for size is 1.
TINYINT(size)A very small integer. Signed range is from -128 to 127. Unsigned range is from 0 to 255. The size parameter specifies the maximum display width (which is 255)
BOOLZero is considered as false, nonzero values are considered as true.
BOOLEANEqual to BOOL
SMALLINT(size)A small integer. Signed range is from -32768 to 32767. Unsigned range is from 0 to 65535. The size parameter specifies the maximum display width (which is 255)
MEDIUMINT(size)A medium integer. Signed range is from -8388608 to 8388607. Unsigned range is from 0 to 16777215. The size parameter specifies the maximum display width (which is 255)
INT(size)A medium integer. Signed range is from -2147483648 to 2147483647. Unsigned range is from 0 to 4294967295. The size parameter specifies the maximum display width (which is 255)
INTEGER(size)Equal to INT(size)
BIGINT(size)A large integer. Signed range is from -9223372036854775808 to 9223372036854775807. Unsigned range is from 0 to 18446744073709551615. The size parameter specifies the maximum display width (which is 255)
FLOAT(sized)A floating point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter. This syntax is deprecated in MySQL 8.0.17, and it will be removed in future MySQL versions
FLOAT(p)A floating point number. MySQL uses the p value 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(). If p is from 25 to 53, the data type becomes DOUBLE()
DOUBLE(sized)A normal-size floating point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter
DOUBLE PRECISION(sized)
DECIMAL(sized)An exact fixed-point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter. The maximum number for size is 65. The maximum number for d is 30. The default value for size is 10. The default value for d is 0.
DEC(sized)Equal to DECIMAL(size,d)

Note: All the numeric data types may have an extra option: UNSIGNED or ZEROFILL. If you add the UNSIGNED option, MySQL disallows negative values for the column. If you add the ZEROFILL option, MySQL automatically also adds the UNSIGNED attribute to the column.

Date and Time data types:

Data typeDescription
DATEA date. Format: YYYY-MM-DD. The supported range is from ‘1000-01-01’ to ‘9999-12-31’
DATETIME(fsp)A date and time combination. Format: YYYY-MM-DD hh:mm:ss. The supported range is from ‘1000-01-01 00:00:00’ to ‘9999-12-31 23:59:59’. Adding DEFAULT and ON UPDATE in the column definition to get automatic initialization and updating to the current date and time
TIMESTAMP(fsp)A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch (‘1970-01-01 00:00:00’ UTC). Format: YYYY-MM-DD hh:mm:ss. The supported range is from ‘1970-01-01 00:00:01’ UTC to ‘2038-01-09 03:14:07’ UTC. Automatic initialization and updating to the current date and time can be specified using DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP in the column definition
TIME(fsp)A time. Format: hh:mm:ss. The supported range is from ‘-838:59:59’ to ‘838:59:59’
YEARA year in four-digit format. Values allowed in four-digit format: 1901 to 2155, and 0000.
MySQL 8.0 does not support year in two-digit format.

SQL Server Data Types

String data types:

Data typeDescriptionMax sizeStorage
char(n)Fixed width character string8,000 charactersDefined width
varchar(n)Variable width character string8,000 characters2 bytes + number of chars
varchar(max)Variable width character string1,073,741,824 characters2 bytes + number of chars
textVariable width character string2GB of text data4 bytes + number of chars
ncharFixed width Unicode string4,000 charactersDefined width x 2
nvarcharVariable width Unicode string4,000 characters
nvarchar(max)Variable width Unicode string536,870,912 characters
ntextVariable width Unicode string2GB of text data
binary(n)Fixed width binary string8,000 bytes
varbinaryVariable width binary string8,000 bytes
varbinary(max)Variable width binary string2GB
imageVariable width binary string2GB

Numeric data types:

Data typeDescriptionStorage
bitInteger that can be 0, 1, or NULL
tinyintAllows whole numbers from 0 to 2551 byte
smallintAllows whole numbers between -32,768 and 32,7672 bytes
intAllows whole numbers between -2,147,483,648 and 2,147,483,6474 bytes
bigintAllows whole numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,8078 bytes
decimal(p,s)Fixed precision and scale numbers.Allows numbers from -10^38 +1 to 10^38 –1.

The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18.

The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0

5-17 bytes
numeric(p,s)Fixed precision and scale numbers.Allows numbers from -10^38 +1 to 10^38 –1.

The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18.

The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0

5-17 bytes
smallmoneyMonetary data from -214,748.3648 to 214,748.36474 bytes
moneyMonetary data from -922,337,203,685,477.5808 to 922,337,203,685,477.58078 bytes
float(n)Floating precision number data from -1.79E + 308 to 1.79E + 308.The n parameter indicates whether the field should hold 4 or 8 bytes. float(24) holds a 4-byte field and float(53) holds an 8-byte field. Default value of n is 53.4 or 8 bytes
realFloating precision number data from -3.40E + 38 to 3.40E + 384 bytes

Date and Time data types:

Data typeDescriptionStorage
datetimeFrom January 1, 1753 to December 31, 9999 with an accuracy of 3.33 milliseconds8 bytes
datetime2From January 1, 0001 to December 31, 9999 with an accuracy of 100 nanoseconds6-8 bytes
smalldatetimeFrom January 1, 1900 to June 6, 2079 with an accuracy of 1 minute4 bytes
dateStore a date only. From January 1, 0001 to December 31, 99993 bytes
timeStore a time only to an accuracy of 100 nanoseconds3-5 bytes
datetimeoffsetThe same as datetime2 with the addition of a time zone offset8-10 bytes
timestampStores a unique number that gets updated every time a row gets created or modified. The timestamp value is based upon an internal clock and does not correspond to real time. Each table may have only one timestamp variable

Other data types:

Data typeDescription
sql_variantStores up to 8,000 bytes of data of various data types, except text, ntext, and timestamp
uniqueidentifierStores a globally unique identifier (GUID)
xmlStores XML formatted data. Maximum 2GB
cursorStores a reference to a cursor used for database operations
tableStores a result-set for later processing

Microsoft Access Data Types

Data typeDescriptionStorage
TextUse for text or combinations of text and numbers. 255 characters maximum
MemoMemo is used for larger amounts of text. Stores up to 65,536 characters. Note: You cannot sort a memo field. However, they are searchable
ByteAllows whole numbers from 0 to 2551 byte
IntegerAllows whole numbers between -32,768 and 32,7672 bytes
LongAllows whole numbers between -2,147,483,648 and 2,147,483,6474 bytes
SingleSingle precision floating-point. Will handle most decimals4 bytes
DoubleDouble precision floating-point. Will handle most decimals8 bytes
CurrencyUse for currency. Holds up to 15 digits of whole dollars, plus 4 decimal places. Tip: You can choose which country’s currency to use8 bytes
AutoNumberAutoNumber fields automatically give each record its own number, usually starting at 14 bytes
Date/TimeUse for dates and times8 bytes
Yes/NoA logical field can be displayed as Yes/No, True/False, or On/Off. In code, use the constants True and False (equivalent to -1 and 0). Note: Null values are not allowed in Yes/No fields1 bit
Ole ObjectCan store pictures, audio, video, or other BLOBs (Binary Large OBjects)up to 1GB
HyperlinkContain links to other files, including web pages
Lookup WizardLet you type a list of options, which can then be chosen from a drop-down list4 bytes