SQL executes well in MS Access but not in C# when "Validation Rule" is set

Question

I am having a strange problem. I have written a query in MS Access which inserts a value perfectly in database when run from MS Access, but when same query is executed from C# then it shows the "Validation Text" as OleDbException and insert command fails. The "Validation Rule" is "@.*" The column saves emails which should have one "@" and one dot "." after it. There is no problem when "Validation Rule" is removed and query is executed from C#. It only occurs when Validation Rule is set and error occurs only from C# and not from MS Access query execution.

I have uploaded the code and database to: http://www.2shared.com/file/XYmFD8Mg/Database_Validation.html

SQL Query in MS Access:

INSERT INTO EMail ( EMail, Company )
VALUES ('bbb@qwerty.com', 'Company');

The code is:

    try
    {
        string dbPath = null;

        if (File.Exists(Path.GetFullPath(@"..\..\..\Database.accdb")))
            dbPath = Path.GetFullPath(@"..\..\..\Database.accdb");

        dbConnection = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + dbPath);
        dbConnection.Open();

        if (0 >= new System.Data.OleDb.OleDbCommand("INSERT INTO EMail ( EMail, Company ) VALUES ('bbb@qwerty.com', 'Company')", dbConnection).ExecuteNonQuery())
            MessageBox.Show("Could not insert 'bbb@qwerty.com'. Check if already inserted.");

        try { dbConnection.Close(); }
        catch (Exception) { }
    }
    catch (Exception Ex)
    {
        try { dbConnection.Close(); }
        catch (Exception) { }

        MessageBox.Show(Ex.Message);
    }

Database snapshot:

Answer 1

You are right, I can confirm the behaviour.

I did a few tests and, apparently, if you change the validation rule to

Like "%@%.%"

it works in C#, but it won't work in Access anymore. I guess the reason is that Access uses DAO for data access, which uses * as the wildcard character, whereas OLEDB's wildcard character is %.

I found that the following validation rule produces the desired result in both Access and .NET:

Like "*@*.*" Or Like "%@%.%"