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.
MySQL Data Types
SQL general data types consist of the following:
- A text- and/or numeric-based value, often referred to as a STRING
- A numeric-only value, often referred to as an INTEGER
- A calendar- and/or clock-based value, often reffered to as DATE or TIME
- A database-specific value such as a boolean [two-option] flag, an array that stores multiple values within one data point
Text data types:
| 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 data types:
| 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 |
Date data types:
| 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:MI: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:MI: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:MI: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 |
Finally, there are a few other data types that you will use:
Other Data Types
BOOLEAN
| Stores TRUE or FALSE values
|
ARRAY
| A set-length and ordered collection of elements |
MULTISET
| A variable-length and unordered collection of elements |
XML
| Stores XML data |
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Which data type holds a variable amount of data from 0 to 65535 characters?
The signed range of SMALLINT is from -32768 to 32767 and the unsigned range is from 0 to 65535. The maximum display length of SMALLINT is also 255.
Which data type is has limit of 65535 characters?
TEXT: 65,535 characters - 64 KB
The standard TEXT data object is sufficiently capable of handling typical long-form text content. TEXT data objects top out at 64 KB [expressed as 2^16 -1] or 65,535 characters and requires a 2 byte overhead.
What datatype is used to store up to 64000 characters?
Up to about 1 gigabyte [GB], but controls to display a long text are limited to the first 64,000 characters. Numeric data.
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Data types for Access desktop databases..
What is VARCHAR data type?
The VARCHAR data type stores character strings of varying length that contain single-byte and [if the locale supports them] multibyte characters, where m is the maximum size [in bytes] of the column and r is the minimum number of bytes reserved for that column.