Error validating database
In computer science, data validation is the process of ensuring data have undergone data cleansing to ensure they have data quality, that is, that they are both correct and useful.
It uses routines, often called "validation rules" "validation constraints" or "check routines", that check for correctness, meaningfulness, and security of data that are input to the system.
A judgement as to whether data is valid is made possible by the validation program, but it cannot ensure complete accuracy.
This can only be achieved through the use of all the clerical and computer controls built into the system at the design stage.
For example, many database systems allow the specification of the following l (plus, minus, and parentheses).
A text field such as a personal name might disallow characters such a markup-based security attack.These additional validity constraints may involve cross-referencing supplied data with a known look-up table or directory information service such as LDAP.For example, an experienced user may enter a well-formed string that matches the specification for a valid e-mail address, as defined in RFC 5322 but that well-formed string might not actually correspond to a resolvable domain connected to an active e-mail account.Whether a grade is correct can only be established by clerical checks or by reference to other files.
During systems design, therefore, data definitions are established which place limits on what constitutes valid data.A validation process involves two distinct steps: (a) Validation Check and (b) Post-Check action.