AFIELDS()

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`AFIELDS()`

This function puts information about table structure into an array. Read it as “Array from fields.” In Visual FoxPro, this function returns a lot more information than in previous FoxPro versions.

Usage

nFieldCount = AFIELDS( ArrayName [, cAlias | nWorkarea ] )

Parameter	Value	Meaning
ArrayName	Array Name	The array to hold table structure information.
cAlias	Character	The alias of the table whose structure information is placed in ArrayName.
cAlias	Omitted	If nWorkarea is also omitted, use current work area.
nWorkarea	Numeric	The number of the work area containing the table whose structure information is placed in ArrayName.
nWorkarea	Omitted	If cAlias is also omitted, use current work area.
nFieldCount	Positive number	The number of rows in the array, which is the number of fields in the specified table.

In VFP 5 and later, the resulting array has 16 columns. In VFP 3, the array has only the first 11 of these columns.

Column	Type	Meaning
1	Character	Field name.
2	Single Character	Field type (see TYPE() for a list of field types).
3	Numeric	Field size.
4	Numeric	Decimal places.
5	Logical	Nulls allowed?
6	Logical	Code page translation NOT allowed?
7	Character	Field Validation rule (from DBC).
8	Character	Field Validation text (from DBC).
9	Character	Field Default value (from DBC).
10	Character	Table Validation rule (from DBC).
11	Character	Table Validation text (from DBC).
12	Character	Long table name (from DBC).
13	Character	Insert Trigger expression (from DBC).
14	Character	Update Trigger expression (from DBC).
15	Character	Delete Trigger expression (from DBC).
16	Character	Table Comment (from DBC).

The sixth column indicates whether code page translation is allowed, but it uses a sort of double negative. In other words, this column is .T. if the field has the NOCPTRANS attribute, which happens if you define it as Character (binary) or Memo (binary). TYPE() doesn’t supply this information, so you need to use either AFIELDS(), COPY STRUCTURE EXTENDED or SET(“NOCPTRANS”) to find out which fields have this attribute. All the columns from 10 to the end contain table-level information and are filled in only for the first field of the table (the first array row). We’re not really sure why this information is returned by AFIELDS() at all. DBGetProp() returns the information, so it’s already available, though not in array form. We guess it’s to make it possible to use AFIELDS(), followed by CREATE TABLE with the FROM ARRAY clause.

As discussed in “DBF, FPT, CDX, DBC—Hike!,” tables that contain nullable fields also have a hidden system field called _NullFlags. Note that this field is not returned by AFIELDS() (it wouldn’t be very well hidden if it was, now, would it?) and therefore routines that think they can add the values returned from AFIELDS() to calculate the size of a DBF will break. Check out RECSIZE() instead.

The same array is created for a FREE TABLE as for a table contained in a database, but the columns marked “(from DBC)” in the table above are empty, in that case.

Example

SELECT Customer
= AFIELDS(aCustFlds)  && structure array for Customer
USE MyTable IN 0
= AFIELDS(aMyStruc, "MyTable")  && structure array for MyTable

AFIELDS()

Usage

Example

See Also

`AFIELDS()`