Understanding Integrity Constraints


Now that you know how to modify data in place, you might be wondering how you can protect or ensure the integrity of your data when it is modified. Integrity constraints are rules that you can specify in order to restrict the data values that can be stored for a variable in a data set. SAS enforces integrity constraints when values that are associated with a variable are added, updated, or deleted using techniques that modify data in place, such as the following:
  • a DATA step with the MODIFY statement
  • an interactive data editing window
  • PROC SQL with the INSERT INTO, SET, or UPDATE statements
When you add an integrity constraint to the table that contains data, SAS ...

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