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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).
Illustrate different types of Locks in SQL Server. There are three kinds of locks in SQL Server i.) Shared locks - These are used for operations which don't allow any update
In an E-R diagram how attributes are represented ? In an E-R diagram attributes are represented in a ellipse.
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Express the following queries in SQL: (a) Write the SQL code that will create ALL the four tables given in the appendix. Your answer should not contain the primary key and
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How do you find the final model after iterative analysis? Why is iterative analysis of any of the problem needed? The final model serves as the base for system architectur
Hardware failure : Hardware failures are the failures when some disk or hardware chip fails. This may result in loss of data. One such trouble can be that a disk gets damaged and
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