Preventing identical records


I would like the users on my website to be able to change their username to anything they desire. But how do I prevent identical usernames?

I know how to update a database, but how to check for identical records, thats the thing!

Any help highly appreciated!!


Who is Participating?
TerryInOhioConnect With a Mentor Commented:
I use Access too.

Public cnnTig As ADODB.Connection
dim strUserNameEntered as String
Public Const DB_PROVIDER = "Microsoft.Jet.OLEDB.4.0"
Public Const StrDataBaseDirectory = "C:\Benefits"

strConnectionString = "Provider=" & DB_PROVIDER & ";Data Source=" & StrDataBaseDirectory & "\" & DB_NAME

cnnTig.Open strConnectionString
strSQL = "SELECT * FROM UsersTable where UserName = '" &  strUserName & "'"
RSwork.Open strSQL, cnnTig, adOpenStatic, adLockOptimistic, adCmdText
If RSwork.RecordCount < 1 Then
       RSwork.Fields("UserName").Value = strUserName
       Msgbox "Use Id " & strUserName & " has been added to the database".
       Msgbox "Use Id " & strUserName & " Already Exists in the database".
end if
Set RsWork = Nothing

If the field that you have the username stored in as a unique key - if you try to insert a duplicate record then you will get an error message if it is duplicated - so if you capture this error then you will know it already exists.

To make sure they did not choose the same user name as another person, do a querry on the database if you come back with 0 records, no one has it and it is safe to insert.  If you come back with a record then put up a message that it is in use.
Cloud Class® Course: Microsoft Office 2010

This course will introduce you to the interfaces and features of Microsoft Office 2010 Word, Excel, PowerPoint, Outlook, and Access. You will learn about the features that are shared between all products in the Office suite, as well as the new features that are product specific.

Ariful AmbiaHead of MISCommented:
      U don’t tell what database ur using. If you use MS SQL server u can follow the steps below.
1. When u create unique constraint u will get a constraint name say “IX_TblUser”

2. Put your Update code in Try catch. When the Try catch got any error due to violation of the constraint “IX_TblUser” it will automatically give u a error with description that the “IX_TblUser” constraint has been violated so this transaction can’t be execute.

3. Create a function (say ErrorEncodedDesc(ErrorDes as String) AS string) which will parse the error description that is given by the database and look for predefine constraint names to match. And when get a match a more user friendly message will return for the function. For example when the “IX_TblUser” constraint violated the error description will pass into the ErrorDes parameter of the function ErrorEncodedDesc. The function will then look for the constraint IX_TblUser in the error description string. When it finds a match the function will return a clearer message to the user say (User name already exists.)

4. After giving the Clear message to the user that the Update failed due to this and this, u don’t have to anything farther coz database already reject the Update.

Hope it will help u.


after putting value in username and password,
do the following steps,
1> check in the database weather ther username is exists or not.
       like : select * from user where username='username';
2>Fire above quary and bind the recordset or datatable
      If recordset or datatable length is greater then 0 then username exists in the database and put the appropriate message.
      IF recordset or datatable length is 0 then username not exists in the database , so u can allow this username

micambAuthor Commented:
Thanx for all the quick responses!

I'm using access at the moment. How would the query look doing that?


Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.