select command

[florivucu]

Hi,
I'm new in VB so my question can be easy for you. I need to select some columns from a table and in where clause I might have a lot of columns. I created more than one select for this job but I suppose there is a way to create only one:
My select is big but let's say I have 3 column for the where clause. First I can select having only one in the where clause, second I have 2 of them and in the end I have all of them. How can I create a single select for all 3?

[DataMiser]

It would help if you had showed your select and where clauses but I can give you a basic example.

Select Field1,Field2 .... From TableName Where Field1=Value And Field2=Value And Field3=Value

This assumes that you only want the records where all 3 fields match the given values You could use OR in place of And or a combination of the 2 depending on what you want.

[florivucu]

Well it's not like that. I have to select and I want to combine them.
first select:
select ... from tablename where field1 = value1 (given the codition the user asked)
and the second, if the user asked (to query) for field2 is with field2.
select ... from tablename where field2 = value2 (given the codition the user asked)
But the user can ask for the first field, or for the second or for both. I want a single select for all 3. I'm thinking at the where clause like a string....

[DataMiser]

So you need the select statement to be built after the user selects something.
You could make your where clause a seperate string then combine it with the select portin basd on the users selection.

Dim strSelect as String
Dim strWhere as String

strSelect="Select  ..... from tablename "
If UserChoice1 Then
    strWhere="Where Filed1=Value"
ElseIf UserChoice2 Then
    strWhere="Where Filed2=Value"
End If
strSelect=strSelect & strWhere

You could also just use a variable for the fieldname and insert that at runtime.

[florivucu]

Yes, the user can select one or many items. Depending on this I have to select the lines. Thanks. I'll try.
Is there a way to combine the conditions in only one? I want to say: in the first select I need the field1 value but not in the second one. Can I say field1 = value if value is not null and field1 = field1 is value is null? Like the if condition?!