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


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


    SQL Data Types

    Each column in a database table is required to have a name and a data type.

    An SQL developer must decide what type of data that will be stored inside each column when creating a table. The data type is a guideline for SQL to understand what type of data is expected inside of each column, and it also identifies how SQL will interact with the stored data.

    Note: Data types might have different names in different database. And even if the name is the same, the size and other details may be different! Always check the documentation!


    MySQL Data Types (Version 8.0)

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

    String data types:

    Data type Description
    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.
    TINYBLOB For BLOBs (Binary Large OBjects). Max length: 255 bytes
    TINYTEXT Holds 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
    MEDIUMTEXT Holds a string with a maximum length of 16,777,215 characters
    MEDIUMBLOB For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data
    LONGTEXT Holds a string with a maximum length of 4,294,967,295 characters
    LONGBLOB For 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 type Description
    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)
    BOOL Zero is considered as false, nonzero values are considered as true. 
    BOOLEAN Equal 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 sizeparameter 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(size, d) 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(size, d) 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(size, d)  
    DECIMAL(size, d) 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(size, d) 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 type Description
    DATE A 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'
    YEAR A 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 type Description Max size Storage
    char(n) Fixed width character string 8,000 characters Defined width
    varchar(n) Variable width character string 8,000 characters 2 bytes + number of chars
    varchar(max) Variable width character string 1,073,741,824 characters 2 bytes + number of chars
    text Variable width character string 2GB of text data 4 bytes + number of chars
    nchar Fixed width Unicode string 4,000 characters Defined width x 2
    nvarchar Variable width Unicode string 4,000 characters  
    nvarchar(max) Variable width Unicode string 536,870,912 characters  
    ntext Variable width Unicode string 2GB of text data  
    binary(n) Fixed width binary string 8,000 bytes  
    varbinary Variable width binary string 8,000 bytes  
    varbinary(max) Variable width binary string 2GB  
    image Variable width binary string 2GB  

    Numeric data types:

    Data type Description Storage
    bit Integer that can be 0, 1, or NULL  
    tinyint Allows whole numbers from 0 to 255 1 byte
    smallint Allows whole numbers between -32,768 and 32,767 2 bytes
    int Allows whole numbers between -2,147,483,648 and 2,147,483,647  4 bytes
    bigint Allows whole numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807  8 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
    smallmoney Monetary data from -214,748.3648 to 214,748.3647  4 bytes
    money Monetary data from -922,337,203,685,477.5808 to 922,337,203,685,477.5807 8 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
    real Floating precision number data from -3.40E + 38 to 3.40E + 38 4 bytes

    Date and Time data types:

    Data type Description Storage
    datetime From January 1, 1753 to December 31, 9999 with an accuracy of 3.33 milliseconds 8 bytes
    datetime2 From January 1, 0001 to December 31, 9999 with an accuracy of 100 nanoseconds 6-8 bytes
    smalldatetime From January 1, 1900 to June 6, 2079 with an accuracy of 1 minute 4 bytes
    date Store a date only. From January 1, 0001 to December 31, 9999 3 bytes
    time Store a time only to an accuracy of 100 nanoseconds 3-5 bytes
    datetimeoffset The same as datetime2 with the addition of a time zone offset 8-10 bytes
    timestamp Stores 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 type Description
    sql_variant Stores up to 8,000 bytes of data of various data types, except text, ntext, and timestamp
    uniqueidentifier Stores a globally unique identifier (GUID)
    xml Stores XML formatted data. Maximum 2GB
    cursor Stores a reference to a cursor used for database operations
    table Stores a result-set for later processing

    Microsoft Access Data Types

    Data type Description Storage
    Text Use for text or combinations of text and numbers. 255 characters maximum  
    Memo Memo is used for larger amounts of text. Stores up to 65,536 characters. Note: You cannot sort a memo field. However, they are searchable  
    Byte Allows whole numbers from 0 to 255 1 byte
    Integer Allows whole numbers between -32,768 and 32,767 2 bytes
    Long Allows whole numbers between -2,147,483,648 and 2,147,483,647 4 bytes
    Single Single precision floating-point. Will handle most decimals  4 bytes
    Double Double precision floating-point. Will handle most decimals 8 bytes
    Currency Use for currency. Holds up to 15 digits of whole dollars, plus 4 decimal places. Tip: You can choose which country's currency to use 8 bytes
    AutoNumber AutoNumber fields automatically give each record its own number, usually starting at 1 4 bytes
    Date/Time Use for dates and times 8 bytes
    Yes/No A 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 fields 1 bit
    Ole Object Can store pictures, audio, video, or other BLOBs (Binary Large OBjects) up to 1GB
    Hyperlink Contain links to other files, including web pages  
    Lookup Wizard Let you type a list of options, which can then be chosen from a drop-down list 4 bytes





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