Visual FoxPro Data and Field Types
All data in Visual FoxPro have a particular data type, which defines the values permitted for the data and the range and size of those values. After you identify and specify the data type you are using, Visual FoxPro can efficiently store and manipulate the data.
When you create a table, you can specify the type of data to be stored in each field of the table. You can specify more data types for fields in a table than for variables and arrays. Variables and arrays can store only a subset of the available Visual FoxPro data types; however. The value you store in a variable or array element determines the type of data in the variable or array element. For more information, see Choosing Data Types.
Tip You can use the TYPE( ) function to determine the type of data stored in a variable, array element, or field.
The following table lists the data types in Visual FoxPro.
Visual FoxPro Data Types
| Data type | Description | Size | Range |
|---|---|---|---|
| Character | Alphanumeric text
For example, a customer address |
1 byte per character to 254 | Any characters |
| Currency | Monetary amounts
For example, the price of an item |
8 bytes | - $922337203685477.5807 to $922337203685477.5807 |
| Date | Chronological data consisting of month, day, and year
For example, an order date |
8 bytes | When using strict date formats, {^0001-01-01}, January 1st, 1 A.D to {^9999-12-31}, December 31st, 9999 A.D. |
| DateTime | Chronological data consisting of month, day, year, hours, minutes, and seconds
For example, date and time of arrival |
8 bytes | When using strict date formats, {^0001-01-01}, January 1st, 1 A.D to {^9999-12-31}, December 31st, 9999 A.D., plus 00:00:00 a.m. to 11:59:59 p.m. |
| Logical | Boolean value of True or False
For example, whether or not an order has been filled |
1 byte | True (.T.) or False (.F.) |
| Numeric | Integers or decimal numbers
For example, the quantity of items ordered |
8 bytes in memory; 1 to 20 bytes in table |
- .9999999999E+19 to .9999999999E+20 |
| Variant | A variant can contain any of the Visual FoxPro data types and the null value. Once a value is stored to a variant, the variant assumes the data type of the data it contains.
Variants are designated with an e prefix in language syntax. |
See data types above. | See data types above. |
In addition, Visual FoxPro provides data types that apply only to fields in tables.
Visual FoxPro Field Types
| Field type | Description | Size | Range |
|---|---|---|---|
| Character (Binary) | Any Character data that you do not want translated across code pages
For example, user passwords stored in a table and used in different countries or regions |
1 byte per character to 254 | Any characters |
| Double | A double-precision floating-point number
For example, scientific data requiring a high degree of precision |
8 bytes | +/-4.94065645841247E-324 to +/-8.9884656743115E307 |
| Float | Same as Numeric | 8 bytes in memory; 1 to 20 bytes in table |
- .9999999999E+19 to .9999999999E+20 |
| General | Reference to an OLE object
For example, a Microsoft Excel worksheet |
4 bytes in table | Limited by available memory |
| Integer | Numeric value with no decimals
For example, a line number in an order |
4 bytes | -2147483647 to 2147483647 |
| Integer (Autoinc) | Same as Integer but also an automatically incrementing value. Read-only. | 4 bytes | Value controlled by autoincrement Next and Step values. |
| Memo | Alphanumeric text of indeterminate length or reference to a block of data
For example, notes about a phone call in a phone log |
4 bytes in table | Limited by available memory |
| Memo (Binary) | Same as Memo except that memo field data does not change across code pages
For example, a login script used in different countries or regions |
4 bytes in table | Limited by available memory |
Each data type has its own characteristics, including storage size:
Data Type Storage Differences
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To see a list of the functions you can use with each data type, see Language Categories.