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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).
What are the Requirements of algorithm designer Algorithm designer should: i) Select proper algorithm so as to minimize implementation cost ii) Find most appropriate d
Key to represent relationship amongs tables is called ? A Key that represent the relationship between tables is called Foreign Key.
Describe the types of attributes? Types of attributes: An attribute's category determines the type of values that are permitted in the attribute. For instance, the value vers
You are required to program (in a high level language such as C, C++, Java) and implement a cache simulator which will have the following inputs and outputs:- INPUTS
About Attribute inheritance
Modify a sequence: ALTER SEQUENCE SEQSS INCREMENT 2 MAXVALUE 3000; Removing a sequence: DROP SEQUENCE SEQSS;
What is a cascading update? Referential integrity constraints needs that foreign key values in one table correspond to primary key values in another. If the value of the primar
Atomicity: It describes a transaction to be a one unit of processing. We can also say either a transaction will be finished completely or not at all. In the transaction example 1
Draw the precedence graph of the following schedule and determine whether the schedule is serializable. (Note that all instructions, except lock and unlock, are omitted. We assume
What is an ERD?
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