Recently we ran into a problems with a user adding products to an Account tab on the web client. The exact error was - The statement has been terminated : string or binary data would be truncated. What the user was attempting to do was add several products in a multiple picklist field and the web client new the data exceeded the length of the field. Here are the steps we took to correct the issue.
1. In the Administrator open the DB Manager
2. Under the Account listing click on the plus sign and open the Prod_Account_Ext table
3. Find the Product Field, rt click, choose properties, and change the Field Length to 256
4. Click OK to close the Product Field window
5. At the top of the Database Manager find the Apply Changes Arrow and Click it
6. Close the Administrator
7. Open the Application Architect and Rebuild the web platform, deploy the slxclient, and run an iisreset.
This method can be used to increase the size of VarChar fields. A word of caution, only perform these steps on a quite system and always create a backup first.