Functions.DbFieldInfo Method

 FUNCTION DbFieldInfo(
	kInfoType,
	nFieldPos,
	uNewSetting
) AS USUAL CLIPPER

[ClipperCallingConventionAttribute(new string[] { ... })]
public static Usual DbFieldInfo(
	Usual kInfoType = default,
	Usual nFieldPos = default,
	Usual uNewSetting = default
)

Parameters

kInfoType (Optional)

Type: Usual
Specifies the type of information.
The constants are described in the Constants section below. Note, however, that not all constants are supported for all RDDs.
Important! DBS_USER is a constant that returns the minimum value that third-party RDD developers can use for defining new kInfoType parameters. Values less than DBS_USER are reserved for Computer Associates development.

nFieldPos (Optional)

Type: Usual
The position of the field in the database file structure or a numeric pointer to a BLOB. Only certain kInfoType constants designed to work with BLOB fields — all noted in the Constants section below — allow specifying the field using a pointer; all others require specifying the field by its position.

uNewSetting (Optional)

Type: Usual
If specified, this parameter is used to change the value of a setting.
The data type (and whether uNewSetting can be specified), depends on the kInfoType constant and is documented in the Constants section below.

DBS_ALIAS Returns and optionally changes an alternate name (or alias) by which a field can be referenced (by default, same as DBS_NAME).
Using the uNewSetting argument, you can specify a string that you can subsequently use to access the indicated field.
DBS_BLOB_DIRECT_LEN Returns the length of data in a BLOB as an unsigned long integer, without referencing a particular memo field.
For strings, the return value is the length of the string in bytes; for arrays, it is the number of elements in the first dimension; for all other data types, it returns -1. With this constant, you must specify the BLOB using a numeric pointer obtained from BLOBDirectPut(), BLOBDirectImport(), or DBFieldInfo(DBS_BLOB_POINTER, nFieldPos).
DBS_BLOB_DIRECT_TYPE To determine the data type of BLOB data, without reference to a particular memo field, use DBFieldInfo(DBS_BLOB_DIRECT_TYPE, ...). With this constant, you must specify the BLOB using a numeric pointer obtained from BLOBDirectPut(), BLOBDirectImport(), or DBFieldInfo(DBS_BLOB_POINTER, nFieldPos).
See DBS_BLOB_TYPE for a table of possible return values.
DBS_BLOB_LEN Returns the length of the BLOB data in a memo field as an unsigned long integer.
For strings, the return value is the length of the string in bytes; for arrays, it is the number of elements in the first dimension; for all other data types, it returns -1.
Note:DBFieldInfo(DBS_BLOB_LEN, ...) has a performance advantage over the Len() function.
DBS_BLOB_POINTER Returns a numeric pointer to the BLOB data associated with a memo field.
DBS_BLOB_TYPE Unlike memo fields maintained in .DBT files, BLOB files allow you to store many different types of data in memo fields. However, the standard functions for determining data types, such as ValType(), simply treat BLOB fields as regular memo fields.
To determine the actual type of BLOB data stored in a memo field, use DBFieldInfo(DBS_BLOB_TYPE, ...).
The data type of the return value is string and can be interpreted using this table:
Returns Meaning
? Blank (empty/uninitialized field)
A Array
C String
D Date
E Error
L Logical
N Numeric
U Undefined (NIL was stored)
DBS_DEC Returns the number of decimal places for the field.
DBS_LEN Returns the length of the field.
DBS_NAME Returns the name of the field.
DBS_PROPERTIES Returns the number of properties defined for a field.
DBS_TYPE Returns the data type of the field.

Return Value

Reference