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Table Field Default to ZLS
Is it a bad idea to set all fields, where possible, in a table to default to a ZLS by placing "" in the field's default value when creating a table? I have been working with databases since dBaseII in the '80s and my applications are for in-house use, never to be sold, and not huge file sizes, over a local domain, not clout based, no SQL server. And, I don't want to create complicated VBA to create an SQL that will ignore Nulls, I get by with some VBA but I'm no expert. When I filter by form (sometimes multiple field filters) and I place text in the "filter" text box & requery/refresh in an "OnExit" event, I do not want records with null values for that field to show in the dataset.
My last application included filter-by-form fields that proved to be very difficult due to Null values in the table fields. I was pulling my hair out trying to not show null values for a particular filter field. I don't use the "Form Filter" in the form itself, I find this to be troubling and unstable. I use criteria in the underlying query matched to filter fields in the form header.
What I also find troubling is that fact that when I have a record field with text and I delete all text within the field the value is a ZLS, not Null.
Can anyone give me a valid reason why I shouldn't completely eliminate Null values and force ZLS by default in my table(s) based on above?
Help is appreciated.
Charlie
My last application included filter-by-form fields that proved to be very difficult due to Null values in the table fields. I was pulling my hair out trying to not show null values for a particular filter field. I don't use the "Form Filter" in the form itself, I find this to be troubling and unstable. I use criteria in the underlying query matched to filter fields in the form header.
What I also find troubling is that fact that when I have a record field with text and I delete all text within the field the value is a ZLS, not Null.
Can anyone give me a valid reason why I shouldn't completely eliminate Null values and force ZLS by default in my table(s) based on above?
Help is appreciated.
Charlie
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Thanks Jim, good info. A week ago I did some testing and came to the conclusion that entering text into a field, saving the record, then returning to the same field/record and deleting the text would result in a ZLS, not null. But I tried it again today with different results, manually deleting text results in a null. So now I have to reevaluate the whole ZLS thing.
Seems to me that Access used to have the option "Allow Null Values" in table setup, but I don't see it now.
Charlie
Seems to me that Access used to have the option "Allow Null Values" in table setup, but I don't see it now.
Charlie
I never allow ZLS. Here's the first problem. Visually, you cannot tell the difference between a Null and a ZLS. So, when creating a query I makes creating criteria on a Text field that 'may' contain a ZLS or a Null. I choose to never worry about this, and thus never all ZLS. Unfortunately, I have to deal with ZLS frequently because we get a lot of 'reports' (XLS or CSV files) wherein Text fields contain ZLS. So, during importing, I check for ZLS ("") and convert to Null if necessary.
It PAINS me to no end that Microsoft chose to have the Default for Text data types as Allow ZLS !
mx
It PAINS me to no end that Microsoft chose to have the Default for Text data types as Allow ZLS !
mx
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I'll plan on building an SQL to redefine the WHERE after I change one of the four "filter-by-form" fields in my form. I'll use the iff() function to see if the form's search criteria is null. SQL WHERE criteria will change from Like "*" & [Forms]![frmLeadsList]
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It's not "bad" and it's not "good" either; it depends on what you want to achieve.
Some dislike having nulls anywhere, so they set all fields. That's a valid approach and there's no real downsides other than making a mistake and not filling a field, at which point your app doesn't handle it well because you didn't account for nulls.
But Nulls do indicate something different than a ZLS. A "null" means value unknown. A ZLS is a value.
For example, a middle name. Null means we don't know if there is one or not, but a ZLS means we do know that the person does not have one.
Jim.