Secondary Navigation. 1  Active Duty Dental Care. 2  Guard/Reserve Dental Care. 3  TRICARE Dental Program. 4  TRICARE Retiree Dental Program. 5  Enrolling in the TRICARE Retiree Dental Program. Costs. 6  Dental Benefits for Survivors. 7  Find a Dentist.
â¢ Although char and varchar are character data fields, char is a fixed length data field and varchar is a variable size data field. â¢ Char can store only fixed size non-Unicode string characters, but varchar can store variable sizes of strings.
If the varchar values are numeric then the queries with do the implicit casting without your explicit casting in SQL queries. ex. if the column is varchar(20) and the values inside are numbers, they may appear as 25 for us a developer, but will bimplicitly converted into int. But if some row in the column contained a value say 25a, then there would be an exception raised. So if you are not that sure of the values, you are left with two options. 1. Convert(int,  column name) 2. Cast( column name as int) ( not sure of cast syntax) Let me know if I am unclear.