$WBNULL$

Availability
UPDATE command

Syntax
$wbnull$

Description
Since WBSP engine ignores empty WBF_tablefieldname form fields, it is not possible to delete content of non-numeric field by sending empty string as a WBF_ field value. Therefore WBSP uses $WBNULL$ as a value for WBF_ form field(s) to define which database table fields in current (updated) record should be set to empty string. It does not apply to the numeric fields (to clear them set their value to 0).

Here's an example:

<!--
[FormFields]
WB_BaseName=biblioA.mdb
WB_RcdSet=Titles
WB_Command=Q
-->
<!--WB_BeginTemplate-->
<html>
<body>
<!--WB_BeginDetail-->
<form action="TitlesUpdate.wbsp" method="POST">
<input type="hidden" name="WBF_ImageURL" value="$wbnull$">
<input type="hidden" name="wbf_isbn" value="$wbf[isbn]">
$wbf[Title]<br>
<img src="images/$wbf[imageurl]"><br>
<input type="submit" name="sClrImg" value="Remove image">
</form>
<!--WB_EndDetail-->
<center>$wbnavigator</center>
</body>
</html>