 Related Questions An integrity constraint is a declarative way to define a business rule for a column of a table. Latest Answer : Special requirements for table data:1) allow NULL value2) uniqueness of value3) primary key4) foreign key5) special value size/text/length etc requirementsAll information is stored in Data Dictionary. ... Can an Integrity Constraint be enforced on a table if some existing table data does not satisfy the constraint ? No. NOT NULL Constraint - Disallows Nulls in a table's column.UNIQUE Constraint - Disallows duplicate values in a column or set of columns.PRIMARY KEY Constraint - Disallows duplicate values and Nulls A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls. Latest Answer : A table can have any number unique keys but a single primary key ... UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data.DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted. Latest Answer : Foreign key value must exist as PK value on some other  table...FK value can be null but PK can't ... If a foreign key reference a parent key of the same table is called self-referential integrity constraint. Latest Answer : Self referential integrity constraint refers to two columns related by referential integrity which belong to the same table.For example ManagerId column in employees table is a foreign key which refers to EmployeeId in the same table. ... The condition must be a Boolean expression evaluated using the values in the row being inserted or updated and can't contain sub queries, sequence, the SYSDATE,UID,USER or USERENV SQL functions, or Latest Answer : A check constraint allows you to specify a condition on each row in a table. Note: A check constraint can NOT be defined on a VIEW. The check constraint defined on a table must refer to only columns in that table. It can not refer to columns in other ... No Limit. Latest Answer : You can create any number of check constraintsseparated by AND, OR, or NOT to create more complex conditions. ...
Sponsored Links
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
