Default Value

A default value is the value that is given to a variable, parameter or property in case no other value is given by the user or the application. It makes certain that an entity is never NULL even when the input for which it’s awaiting is not available thus avoiding faults in the system.

Role of Default Values in Programming

In most of the languages, the default values are assigned at the time of declaration or initialization of variables. This is especially the case in object oriented programming where a default state can be set for an object property and thus all objects of the same class will behave in a similar manner.

For instance, if a developer declares a variable but fails to assign it a value then a default value will be assigned to it. This minimizes the possibility of having a variable that has not been given a value or having a value that may lead to an error when the program is using it.

Default Values in Databases

For the case of DBMS, default values are also very useful. When creating a table, the developers can set default constraints for some of the columns. This implies that if a value is not given during data input then the default value of that column will be used. This feature is very helpful in keeping data accuracy and consistency in handling large data set.

For example, in a table that contains user accounts, the status of the account could be set by default to ‘active’. In a case where a new user is created in the database and no account status is provided, the default status will be set as active so that all the accounts are in a known state until changed manually.

Importance of Choosing Appropriate Default Values

It is therefore important that developers spend some time in trying to determine the appropriate default values. The default that has been chosen should be reasonable and pertinent to the system or application that it is implemented in. Bad choices of default values may cause undesirable effects including wrong data processing and users’ confusion.

For instance, in a financial application, initializing a balance column to “0” may be appropriate while in other applications, the same may result in producing wrong values or even fraudulent results. Hence, developers need to consider what default values would be most appropriate to their application.

Conclusion

A default value is a basic concept used in programming as well as in database management to assign a value to a variable, a parameter or a column in a table when another value is not available. It is important to use default values in order to avoid mistakes, to have uniformity and to get expected results from the software applications and databases. Nevertheless, identifying proper default values is important because they have to meet the purpose of the system and not to lead to negative effects.