Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Explain the two constraints, check and foreign key in SQL along with an example for each. Give the syntax.
CHECK constraint - CHECK constraint specifies an expression which must always be true for every row in the table. It can't refer to values within other rows.Syntax:ALTER TABLE ADD CONSTRAINT CHECK();
FOREIGN KEY constraint - A foreign key is a combination of columns along with values based on the primary key values from another table. A foreign key constraint, also called as referential integrity constraint, specifies in which the values of the foreign key correspond to actual values of the primary or unique key in other table. One can refer to a primary or unique key in the similar table also.
Syntax: ALTER TABLE ADD CONSTRAINT FOREIGN KEY()REFERENCES () ON {DELETE | UPDATE}CASCADE;
Multiple column Queries: Syntax: SELECT COLUMN1, COL2,...... FROM TABLE WHERE (COLUMN1, COL2, ...) IN (SELECT COLUMN1, COL2,.... FROM TABLE WHERE );
What are stored and derived attributes? Stored attributes: The attributes keeps in a data base are known as stored attributes. Derived attributes: The attributes that are de
explain normalisation
Need for Multiple Access Paths In practice, most of the online information systems need the support of multi-key files. For example, consider a banking database application hav
During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in
What is recovery management component? Ensuring durability is the responsibility of a software component of the base system known as the recovery management component.
Data slice explanation
Differance between Open addressing and chaining for collision resolution ? In open addressing , proceeding from the occupied position specified by hash address the program che
What sorts of tables one can se in designing the hierarchy of a LDB? Tables, which are having Foreign Key relations.
Define Deadlock recovery measures To recover from deadlock, the cycle in the wait-for-graph should be broken. The common technique of doing this is to rollbac
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd