[<<Previous Entry]
[^^Up^^]
[Next Entry>>]
[Menu]
[About The Guide]
BLOBGET()
Get the contents of a BLOB, identified by its memo field number
------------------------------------------------------------------------------
Syntax
BLOBGet(<nFieldPos>, [<nStart>], [<nCount>]) --> uBLOB
Arguments
<nFieldPos> is the position of the field in the database file
structure.
<nStart> is the starting position in the memo field of the BLOB
data. If <nStart> is positive, the starting position is relative to the
leftmost character in <nFieldPos>. If <nStart> is negative, it is
relative to the rightmost character in <nFieldPos>. If <nStart> is
omitted, it is assumed to be 1.
<nCount> is the number of bytes of data to retrieve beginning at
<nStart>. If <nCount> is larger than the amount of data stored, excess
data is ignored. If omitted, BLOBGET() retrieves to the end of the
data.
Note: <nStart> and <nCount> apply to string data only. They are
ignored for any other data types.
Returns
BLOBGET() returns the BLOB data retrieved from the memo field. The data
type of the return value depends on the actual data stored. Use
VALTYPE() to determine the data type. If the indicated field is not a
memo field, BLOBGET() returns NIL.
Description
BLOBGET() is very similar to FIELDGET(). However, because string type
variables cannot be larger than 64 KB, FIELDGET() will raise a runtime
error when attempting to retrieve memo fields of this magnitude or
greater.
BLOBGET() will also raise an error if you attempt to retrieve a field
greater than this magnitude; however, you can retrieve any subset of the
BLOB data by using an <nCount> less than 64 KB.
Note: BLOB data less than 64 KB can be retrieved from a memo field
using standard means (for example, referring to the field by name in an
expression or using the FIELDGET() function).
By default, this function operates on the currently selected work area.
It can be made to operate on an unselected work area by specifying it
within an aliased expression.
Examples
. This example imports information from a word processing
document into a field, then uses BLOBGET() to extract the first 25
characters of the field:
FUNCTION GETFIRST25()
LOCAL nPos
LOCAL cStr
USE customer NEW VIA "DBFCDX"
// Field that contains word processor
// documentation
nPos := FieldPos("WP_DOC")
// Import a file (can be larger than 64 KB), then
// obtain the first 25 characters to show to the
// user
IF BLOBImport(nPos, "c:\application\temp.doc")
cStr := BLOBGet(nPos, 1, 25)
ELSE
cStr := "Error: could not import file!"
ENDIF
CLOSE
RETURN cStr
See Also:
BLOBDIRECTGET()
BLOBDIRECTPUT()
BLOBIMPORT()
This page created by ng2html v1.05, the Norton guide to HTML conversion utility.
Written by Dave Pearson