From the March 2009 Issue of Prestwood eMag   DBA & Data: dBASE Table Specification By Mike Prestwood 12/12/2006   Take Away: Description of dBASE IV field types DBA KB Post:  Tags: dBASE , table , field types , column descriptions

dBASE IV Table Specification

The dBASE IV table format was introduced in dBASE IV for DOS. Following are the specifications for dBASE IV tables.

• 2GB file size.

• Two billion records per file.

• A maximum of 255 fields per record.

• Maintained indexes can have up to 47 indexes per file. Each index can be created using field expressions of virtually any combination, including conditional expressions of up to 255 characters per expression that result in an index of up to 100 bytes.

• Unlimited nonmaintained indexes can be stored on disk. You can use up to 47 of them simultaneously.

dBase V Table Specifications

The dBASE V table format was introduced in dBASE V for Windows. Following are the specifications for dBASE V tables.

• Up to one billion records per file.

• A maximum of 1,024 fields per record.

• Up to 32,767 bytes per record.

• Unlimited nonmaintained indexes can be stored on disk. You can use up to 47 of them simultaneously.

• Up to 10 master index files open per database. Each master index can have up to 47 indexes.

• Maintained indexes can have up to 47 indexes per file. Each index can be created using field expressions of virtually any combination, including conditional expressions of up to 255 characters per expression that result in an index of up to 100 bytes.

dBASE Field Types

Character (C)

dBASE III+, IV, and V field type that can contain up to 254 characters (including blank spaces). This field is similar to the Paradox Alpha field type.

Date (D)

Paradox 3.5, 4, 5, and 7 as well as dBASE III+, IV, and V. dBASE tables can store dates from January 1, 100, to December 31, 9999. Paradox 5 tables can store from 12/31/9999 B.C. to 12/31/9999 A.D.

Float (F)

dBASE IV, and V floating-point numeric field type provides up to 20 significant digits.

Logical (L)

Paradox 5 and 7 and dBASE III+, IV, and V field type can store values representing True or False (yes or no). By default, valid entries include T and F (case is not important).

Memo (M)

Paradox 4, 5, and 7 as well as dBASE III+, IV, and V field. A Paradox field type is an Alpha variable-length field up to 256MB per field. dBASE Memo fields can contain binary as well as memo data.

OLE (O)

Paradox 1, 5, and 7 as well as dBASE V field type that can store OLE data.

Number (N)

Paradox 3.5, 4, 5, and 7 as well as dBASE III+, IV, and V field type can store up to 15 significant digits -10307 to + 10308 with up to 15 significant digits.

dBASE number fields contain numeric data in a Binary Coded Decimal (BCD) format. Use number fields when you need to perform precise calculations on the field data. Calculations on number fields are performed more slowly but with greater precision than are calculations on float number fields. The size of a dBASE number field can be from 1 to 20. Remember, however, that BCD is in Paradox 5 and 7 only for compatibility and is mapped directly to the Number field type.

Short (S)

Paradox 3.5, 4, 5, and 7 field type that can contain integers from -- 32,767 through 32,767 (no decimal).

KB Post Contributed By Prestwood staff member Mike Prestwood:

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Reader... Georgia Tech WayneW  (Inactive) Wayne Wu Visits: 1 MB Posts: 0 KB Articles: 0 Rank: Cadet 2nd Year Joined: Jun 2003 Location: Atlanta, GA USA

Comment 1 of 1 Wednesday, June 25, 2003 Please also specify the field width limits for dBase IV to dBase VII

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