I am writing a program, and I need to be able to check whether a certain 'tag' exists, by looking at all the 'tags' in the column 'CowTagMain' of the 'CowTable' table.

The code I am using is, DLookup("[CowTagMain]", "[CowTable]", "[CowTagMain]") = Tag ... Where tag is a String, TagMain is the column, and MainTable, is the table I am fetching data from.

I am getting inconsistent results, when I try this with 18C, it returns true. While if I try this with 18, it returns false.

I would assume I am fundamentally misunderstanding how to use DLookup, but after searching the internet for hours I cannot understand what I am doing wrong. Even just pointing me in the right direction would be very appreciated! I am new to working with Access and VBA.

CodePudding user response：

The search criteria is not within the function WHERE CONDITION argument.
The field is text type so need apostrophe delimiters.

Consider:

If IsNull(DLookup("[CowTagMain]", "[CowTable]", "[CowTagMain]= '" & Tag & "'")) Then