Sql validating data against data type

19-Sep-2019 20:30 by 6 Comments

Sql validating data against data type

Each of these allies have their own perimeters which may or may not trust ours. As noted in the Introduction, we trust nothing and nobody.The common phrase you will have seen in PHP is to never trust “user input”.

All possible entrances and exits on the perimeter are guarded day and night by trigger happy sentries who prefer to shoot first and never ask questions.Input Validation is the outer defensive perimeter for your web application.This perimeter protects the core business logic, processing and output generation.So we can do the validation in an IF statement inside the trigger, but how can we cancel the insert/update and throw an error?My SQL 5.5 introduced the handy operator that can be used to do just that.When you define rules for tables, those rules apply when you import data.

To add validation rules to a table, you open the table and use commands on the Fields tab of the ribbon.

My SQL triggers can be used to create some validation conditions that are a little bit more complex than what can be achieved with basic data types and unique index for example.

The reason why data validation is better kept at the database level rather than application level is that in case the same data source is used by multiple applications, or even multiple interfaces within the same application, is that you can rely on the data being consistent and valid regardless the validation logic on the application side, which might not always be consistent across different implementations. Triggers can be executed before data is inserted or updated into the database, and you have the values that would be inserted to the database at your disposal, as well as the old values of the row in case of an update.

It allows to set a specific error condition (or SQLSTATE) and a custom error message.

This is exactly what we need in this case, as it will return a native My SQL error and thus also prevent the insert or update clause (as long as we use it in a trigger that is specified to run before insert or update). If you are still running old versions, the statement when creating the trigger so you can’t use that.

It’s likely that all the additional validation checks will slow down the process of inserting data, which is not a great result.