this is not a good idea for the table design, and is the cause of the issue you are having.
the primary key column of your database should be a numeric column that you set to also auto increment, you want to make sure that the primary key column cannot have duplicate information, it is the unique identifier in your database.
the minimum table set up I would recommend is 2 columns, numeric primary key, Auto Increment column and a text column.
positionID - integer, Primary Key, Not Null, Auto Increment
positionName - varchar(45)