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Explain several types of constraints that can be specified using CREATE TABLE command. Explain CASCADE and RESTRICT clauses of DROP SCHEMA command?Constraint DescriptionPRIMARY KEY Determines that column(s) uniquely identifies each record. The primary key cannot be NULL, and the data value(s) must be unique.
FOREIGN KEY In a one-to-many relationship, the constraint is added to the "many" table. The constraint ensures which if a value is entered into a specified column, it must already exist in the "one" table, or the record is not added.
UNIQUE Ensures that all data values stored in a specified column are unique.The UNIQUE constraint differs from the PRIMARY KEY constraint in which it permits NULL values.CHECK Ensures in which a specified condition is true before the data value is added to a table. For example, an order's ship date cannot be previous than its order date.
NOT NULL Ensures in which a specified column cannon contain a NULL value. The NOT NULL constraint can just be created along with the column-level approach to table creation.
Prevents the DROP from taking place if any dependent objects exists (RESTRICT) or causes all dependent objects do also be dropped (CASCADE).
You want to implement following relationships when designing tables. How would you do it? a.) One-to-one b.) One-to-many c.) Many-to-many a.) One-to-One relationship -
Consider the entity type dependent related to employee entity, which is used to keep track of the dependents of every employee. The attributes of dependents are: name, sex, birth d
management information system based on functional organisation
Define the Immediate Update The immediate update methods may apply changes to the database on disk before the transaction arrives a successful conclusion. Though, these change
Give two profit of Reuse of Code. Reusing the implementation . Place existing class directly inside a new class. The new class can be made up of any number and type of the oth
what is query processing ,query optimization and performance turring?
I have a small project that contains 3 deliverable s. I have done the first one and I would like you to help me with second one
Example : Search the name, department number and salary of employees drawing minimum salary in that department. SELECT ENAME, SAL, DEPTNO FROM EMP WHERE SAL IN (SELECT MI
What is first normal form? The domain of attribute must contain only atomic (simple, indivisible) values.
About Attribute inheritance
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