Understanding Data Constraints

Data constraints limit the values of variables in ways that you specify. Typical examples of data constraints are:

• Limiting a variable's possible values to items on a list that you define.

• Limiting an integer variable to a range of values, such as 1 to 10.

• Limiting a date variable to a range of dates, such as August 5, 2011 to September 30, 2011.

• Limiting the length of a string variable to a specified number of characters, such as 25.

Even if there are additional data constraints, the value of any variable can be NOT SET. However, you can use the required field option to force a variable's value to be set.

The constraints you can add and the procedures for adding them depend on the data type of the variable involved. For more information about adding data constraints to a variable of a particular data type, see the help topic about that data type. Links to the help topics are here.