What is a data base constraint?

#.In the field of relational database design, normalization is a systematic way of ensuring that a database structure is suitable for general-purpose querying and free of certain undesirable characteristics-insertion, update, and deletion anomalies-that could lead to a loss of data integrity. ...

1.database contraints provide a way to guarantee that;-rows in a table have valid primary or unique key value.

2.-rows in a dependent table have valid foreign key values that reference rows in a parent table.

3.-individual column values are valid