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Default Values

A default value is the value that is inserted into a column when an explicit value is not specified in an INSERT statement. A default value can be a literal character string that you define or one of the following SQL constant expressions:

Not all columns need default values, but as you work with your data model, you might discover instances where the use of a default value saves data-entry time or prevents data-entry error. For example, the telephone directory model has a state column. While you look at the data for this column, you discover that more than 50 percent of the addresses list California as the state. To save time, specify the string CA as the default value for the state column.

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