CHECK integrity constraint on a column or set of columns requires that a specified condition be true or unknown for every row of the table. If a DML statement results in the condition of the CHECK constraint evaluating to false, then the statement is rolled back.
a mechanism for allowing predicates to be defined on a column
Specifies data values that are acceptable in a column. You can apply check constraints to multiple columns and you can apply multiple check constraints to a single column. When a table is deleted, all check constraints are also deleted.
A restriction that enforces specified conditions on a column or set of columns. See also: constraint, foreign key constraint, primary key constraint, unique constraint.
A boolean test applied to each row of a table on an insert or update to validate it.
A user-defined condition that must evaluate to true or NULL for a column value to be valid. For example, you can define a constraint to ensure no employee is payed less than the minimum wage, say (salary 1000). If the condition is violated (after an INSERT or UPDATE), the transaction will be rolled back.
Specifies a check condition that is not false for each row of the table on which the constraint has been defined.
A check constraint (also known as table check constraint) is a condition that defines valid data when adding or updating an entry in a table of a relational database. A check constraint is applied to each row in the table. The constraint must be a predicate.