Compare texts string in VB. NET

C

Chong

Well-known member
Joined
Apr 4, 2003
Messages
79
I need help on comparing a word or phrase enter by a user at run time to a MS Access database field format as memo. The Access field contains around a thousand characters of words and/or phrases and I need to compare if there is any match with any of the phrases or words in the memo field of the mdb database. The comparison doesnt have to be exactly match the case, space, order, or the full word or phrase. A great example of what I want to do is the search tool in Windows 2000 when you click Start/Search/For Files or Folders... But in this case I want to compare to a string variable that store the contents of the memo field from my MS Access mdb file.

If anyone has any idea, please give me a helping hand on this issue.

Many thanks in advance!

Chong
 
Assuming your search words are dan and jones and youre searching on a field named memotext, heres what the SQL should look like (use a DataReader or a DataSet/DataAdapter to run the SQL):
Code: 
SELECT * FROM Table1 WHERE memotext LIKE *dan* AND memotext LIKE *jones*

This would assume you want to find records that have BOTH dan and jones. If you want either word, use OR instead of AND above.

-Nerseus
 
Thanks! How would I do the same thing but not in the query? What if I already store the memotext into a string variable, strMemo, how would compare that?

Chong
 
Do you mean a single string variable? You can use the IndexOf method:
Code: 
        Dim s As String
        s = "hello world this is dan jones and I love .NET"

        If s.IndexOf("dan") > 0 And s.IndexOf("jones") > 0 Then
            Debug.WriteLine("Found")
        Else
            Debug.WriteLine("Not Found")
        End If
 
Will the comparison in this code evaluate casesensitivity? I dont want to evaluate casesensitivity and it doesnt have to match the whole word or phrase. For example:

Dim UserString as String
Dim CompareString as String

CompareString = Technology
UserString = Tech

When CompareString and UserString are being compare, I want the result to be true.

Chong
 
IndexOf is case-sensitive. I think youll have to code that type of "in string" comparison yourself, unless VB.NET supports the same InStr function as VB6 along with VB6s "Option Compare Text". Im not that familiar with VB.NET...

If you cant do the query in SQL on the database, can you do it against a column in a DataSet? The DataSets DataTable supports a Select statement that can do the above type of searching client-side. For example (couldnt test this in VB.NET - no sample DataSet projects at the moment):
C#: 
DataRow[] rows = myDataSet.Tables["Table1"].Select("memotext LIKE %dan% AND memotext LIKE %jones%");
if(rows.Length > 0)
	Debug.WriteLine("found");
else
	Debug.WriteLine("not found");

-Nerseus
 
Last edited by a moderator:
To do a case insensitive IndexOf, you could try this:
Code: 
myString.ToUpper.IndexOf(searchForThis.ToUpper)
:-\
 
Back
Top