Using Variables to Send a Query to SQL Server from C/SIDE

Hello. I need some help with using variables to send an Insert query into SQL Server. Let me describe the scenario.

I want to update (periodically) a SQL Server database from inside Nav. I am using ADO to make the connection with success. However, i cant send a query to SQL Server using a variable. Below are the variables i used

Name DataType Subtype Lenght
Cust Record Customer
CustName Text 50

CODE:
WITH Cust DO BEGIN
IF Cust.FIND('-') THEN BEGIN
REPEAT
CustName := Cust."Account Name";
SQLString := 'insert into testdata(texttest) values(CustName)';
ADORecSet := ADOConnection.Execute(SQLString);
UNTIL BankAct.NEXT = 0;
END;
END;

When i run the codeunit, it returns "The Call to member Execute failed. Microsoft OLE DB Provider returned the following message: The Name CustName is not permitted in this context. Only constants, expressions, or variables allowed here. Column names are not permitted"

However, when i use '' '' around CustName, it runs through the table and creates a record each for every customer, except that is uses the literal CustName as the name of all the customer.

Please what do i need to do?

Thank you all in advance.

Melton