sql data types

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SQL Data Types

  • SQL Date

    Data types and ranges for Microsoft Access, MySQL and SQL Server.

  • 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

  • MySQL Data Types

    In MySQL there are three main types : text, number, and Date/Time types.

    Text types:

    Data type Description
    CHAR(size) Holds a fixed length string (can contain letters, numbers, and special characters). The fixed size is specified in parenthesis. Can store up to 255 characters
    VARCHAR(size) Holds a variable length string (can contain letters, numbers, and special characters). The maximum size is specified in parenthesis. Can store up to 255 characters. Note: If you put a greater value than 255 it will be converted to a TEXT type
    TINYTEXT Holds a string with a maximum length of 255 characters
    TEXT Holds a string with a maximum length of 65,535 characters
    BLOB 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(x,y,z,etc.) Let you enter 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.

    Note: The values are sorted in the order you enter them.

    You enter the possible values in this format: ENUM(‘X’,’Y’,’Z’)

    SET Similar to ENUM except that SET may contain up to 64 list items and can store more than one choice

    Number types:

    Data type Description
    TINYINT(size) -128 to 127 normal. 0 to 255 UNSIGNED*. The maximum number of digits may be specified in parenthesis
    SMALLINT(size) -32768 to 32767 normal. 0 to 65535 UNSIGNED*. The maximum number of digits may be specified in parenthesis
    MEDIUMINT(size) -8388608 to 8388607 normal. 0 to 16777215 UNSIGNED*. The maximum number of digits may be specified in parenthesis
    INT(size) -2147483648 to 2147483647 normal. 0 to 4294967295 UNSIGNED*. The maximum number of digits may be specified in parenthesis
    BIGINT(size) -9223372036854775808 to 9223372036854775807 normal. 0 to 18446744073709551615 UNSIGNED*. The maximum number of digits may be specified in parenthesis
    FLOAT(size,d) A small number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
    DOUBLE(size,d) A large number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
    DECIMAL(size,d) A DOUBLE stored as a string , allowing for a fixed decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter

    *The integer types have an extra option called UNSIGNED. Normally, the integer goes from an negative to positive value. Adding the UNSIGNED attribute will move that range up so it starts at zero instead of a negative number.

    Date types:

    Data type Description
    DATE() A date. Format: YYYY-MM-DD

    Note: The supported range is from ‘1000-01-01’ to ‘9999-12-31’

    DATETIME() *A date and time combination. Format: YYYY-MM-DD HH:MM:SS

    Note: The supported range is from ‘1000-01-01 00:00:00’ to ‘9999-12-31 23:59:59’

    TIMESTAMP() *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

    Note: The supported range is from ‘1970-01-01 00:00:01’ UTC to ‘2038-01-09 03:14:07’ UTC

    TIME() A time. Format: HH:MM:SS

    Note: The supported range is from ‘-838:59:59’ to ‘838:59:59’

    YEAR() A year in two-digit or four-digit format.

    Note: Values allowed in four-digit format: 1901 to 2155. Values allowed in two-digit format: 70 to 69, representing years from 1970 to 2069

    *Even if DATETIME and TIMESTAMP return the same format, they work very differently. In an INSERT or UPDATE query, the TIMESTAMP automatically set itself to the current date and time. TIMESTAMP also accepts various formats, like YYYYMMDDHHMMSS, YYMMDDHHMMSS, YYYYMMDD, or YYMMDD.

  • SQL Server Data Types

    Character strings:

    Data type Description Storage
    char(n) Fixed-length character string. Maximum 8,000 characters n
    varchar(n) Variable-length character string. Maximum 8,000 characters  
    varchar(max) Variable-length character string. Maximum 1,073,741,824 characters  
    text Variable-length character string. Maximum 2GB of text data  

    Unicode strings:

    Data type Description Storage
    nchar(n) Fixed-length Unicode data. Maximum 4,000 characters  
    nvarchar(n) Variable-length Unicode data. Maximum 4,000 characters  
    nvarchar(max) Variable-length Unicode data. Maximum 536,870,912 characters  
    ntext Variable-length Unicode data. Maximum 2GB of text data  

    Binary types:

    Data type Description Storage
    bit Allows 0, 1, or NULL  
    binary(n) Fixed-length binary data. Maximum 8,000 bytes  
    varbinary(n) Variable-length binary data. Maximum 8,000 bytes  
    varbinary(max) Variable-length binary data. Maximum 2GB  
    image Variable-length binary data. Maximum 2GB  

    Number types:

    Data type Description Storage
    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 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 table to a cursor used for database operations
    table Stores a result-set for later processing

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