How to write Case Sensitive Query for MS Access?

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耶瑟儿~
耶瑟儿~ 2020-12-03 22:49

I want to know the Select Query for MS Access with case sensitive.

I have two values for VitualMonitorName as below

VCode VirtualMonitorName
Row 1 (1         


        
5条回答
  •  不思量自难忘°
    2020-12-03 23:03

    You can use the StrComp() function with vbBinaryCompare for a case-sensitive comparison. Here is an example from the Immediate window to show how StrComp() works. See the Access help topic for more details.

    ? StrComp("a", "A", vbBinaryCompare)
     1 
    
    ? StrComp("a", "A",vbTextCompare)
    0
    

    StrComp() returns 0 if the first two arguments evaluate as equal, 1 or -1 if they are unequal, and Null if either argument is Null.

    To use the function in a query, supply the vbBinaryCompare constant's value (0) rather than its name.

    SELECT VCode
    FROM VirtualMaster
    WHERE StrComp(VirtualMonitorName, "Vm1", 0) = 0;
    

    This approach is also available to queries from other applications if they use the newer Access Database Engine ("ACE") drivers. For example, the following C# code

    string myConnectionString =
            @"Driver={Microsoft Access Driver (*.mdb, *.accdb)};" +
            @"Dbq=C:\Users\Public\Database1.accdb;";
    using (OdbcConnection con = new OdbcConnection(myConnectionString))
    {
        con.Open();
        using (var cmd = new OdbcCommand())
        {
            cmd.Connection = con;
            cmd.CommandText = 
                    "SELECT COUNT(*) AS n FROM [VirtualMaster] " +
                    "WHERE StrComp([VirtualMonitorName],?,?) = 0";
            cmd.Parameters.AddWithValue("?", "Vm1");
            cmd.Parameters.Add("?", OdbcType.Int);
    
            var vbCompareOptions = new Dictionary() 
            {
                {"vbBinaryCompare", 0},
                {"vbTextCompare", 1}
            };
            string currentOption = "";
    
            currentOption = "vbBinaryCompare";
            cmd.Parameters[1].Value = vbCompareOptions[currentOption];
            Console.WriteLine(
                    "{0} found {1} record(s)", 
                    currentOption, 
                    Convert.ToInt32(cmd.ExecuteScalar()));
    
            currentOption = "vbTextCompare";
            cmd.Parameters[1].Value = vbCompareOptions[currentOption];
            Console.WriteLine(
                    "{0} found {1} record(s)",
                    currentOption,
                    Convert.ToInt32(cmd.ExecuteScalar()));
        }
    }
    

    produces

    vbBinaryCompare found 1 record(s)
    vbTextCompare found 2 record(s)
    

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