asked on

Asp.Net: private function in SQL SELECT statement

Hello experts,
in my Asp.Net (VB.Net) application
I'm using an SQL select statement like

strSQL = "select * from table where (field = '" & strCompare & "'")

but I need an SQL statement like

strSQL = "select * from table where (MyFunction(field) = '" & strCompare & "'")

Private Function MyFunction(strField as String) as String
...
myfunction = "xxx"
End Function

I cannot use a function for strCompare.
I couldn't find a way to have for this a proper syntax.
If anyone knows a solution please supply appropriate [snippet] information.
The database behind is MS Access.

Thank you very much!

HStrix

mmarinov

Hi,

use this
strSQL = "select * from table where (" & MyFunction(field) & " = '" & strCompare & "'")

Regards,
B..M

AerosSaga

I don't see where your returning a value from your function?

AerosSaga

also just run the function directly before the SQL statement and then assign an intermediary variable the value the function returns.

Regards,

Aeros

mAjKoL

I am not quite sure what do you need this function there. Looks like it should return a column name. Am I right?
If so - you could do:
strSQL = "select * from table where (" & MyFunction(field) & "= '" & strCompare & "'")

raterus

Could you use a UDF in sql server? (User Defined Function), or do you have to have this function in VB.

mAjKoL

in SQL Server yes - but this is MS Access

HStrix

ASKER

Perhaps I gave to little information;
"field" represent a database field in the table used in the FROM clause.

For
strSQL = "select * from table where (" & MyFunction(field) & "= '" & strCompare & "'")
I'm getting the error that "field" is not declared.

raterus

You can do that too in Access, you just have to write the function in an Access Module.

HStrix

ASKER

As I mentioned in my question,
the statement is in an Asp.Net (VB.Net) application.
I don't understand what can do in Access.

HStrix

ASKER

The function "MyFunction" also is part of the Asp.Net (VB.Net) application.

mAjKoL

So you have to write it in an Access Module as raterus says. Than you can use it in SELECT statement

raterus

I understand that, but you can't (when you define the query), pull out a returned field from the query. This is not functional syntax.
strSQL = "select * from table where (" & MyFunction(field) & "= '" & strCompare & "'")

What you have to do is first get the results using plain old field, then make a temporary table using your function, then perform the original match.

mAjKoL

This shoul help you:
http://www.di-mgt.com.au/classes.html

ASKER CERTIFIED SOLUTION

raterus

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

HStrix

ASKER

I understand your comments as follows:
In Access I write the function MyFunction in a module MyModule.

But this means, the SQL statement needs to be modified to ???
strSQL = "select * from table where (MyFunction(field) = '" & strCompare & "'")
This looks like a Stored Procedure .. ??

But it cannot be
strSQL = "select * from table where (" & MyFunction(field) & "= '" & strCompare & "'")

Please supply a little bit more information.

raterus

I don't understand what you mean, nothing in that looks like a stored procedure. Oh yeah though, make your function "Public" declared in the module though!

blueforce

What are you trying to accomplish with MyFunction(field) ?

I'm trying to think of an example of why you would do that.

Just an example:

I could assume maybe you have a SocialSecurity field that stores the data as
xxx-xxx-xxxx

And the string your app wants to compare gets passed in as xxxxxxxxxx so you want to format them identically?

Why not format the variable instead of the field?

I just can't figure out why you would want to run a function on a database field then compare a string value to it.

Need more input.

HStrix

ASKER

The problem is related to a date field with different format based on the culture.
So I cannot format the variable, what I made on other places in my application.

raterus

You should be storing dates in a "date" format in the server, also it should NEVER be the job of the database to format the dates in a format the end user will be viewing. If you don't follow these rules, well you get the problems you are running into.

HStrix

ASKER

Thanks to everyone,
I came to the conclusion solving my problem I need to create a new field.

In addition, I agree with your comment raterus concerning the usage of date fields.
I'm also using MySQL and there the date format is independent from the culture and easy to deal with.

HStrix