A data entry rule ensures that the data entered into a column meets the criteria you specify. You can use rules to do the following:

·	Prevent duplicate information from being entered. For example, a new stock number cannot be the same as an existing one.

·	Verify that the data being entered corresponds with data elsewhere in the database. For example, the product stock number must exist in a table before you enter a sales transaction for the product.

·	Prevent a row from being deleted if it corresponds with data elsewhere in the database. For example, if a transaction refers to a customer, the customer cannot be deleted from the customer table.

·	Define a value range. For example, when you enter a salary, it must be between $15,000 and $50,000. You can either specify a maximum value, a minimum value, or a range of values.

When you enter or edit data, R:BASE checks the data you enter with the corresponding rules. If the conditions of a particular rule are not met, R:BASE displays the error message defined for that rule and does not add the row. You can turn the rules setting on or off; the RULES setting must be on for R:BASE to check them.

As you use and modify the tables in your database, you might need to revise the data entry rules. For example, if you rename a column or table used in the WHERE clause of a rule definition, you must update the rule to reflect the change.

You can delete rules that no longer apply to your database. For example, delete rules that are associated with a column you have deleted from a table.

See also

DROP Command

LIST Command

RENAME Command

RULES Command

SET RULES Command