What does a database constraint called a 'CHECK' constraint do? MCQ with Answer and Explanation
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Question #1
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Which SQL statement is used to delete an existing view from the database catalog?
Correct Answer: Option A
Explanation:
Because a View is a database structural object, it is removed from the database schema using the DDL command 'DROP VIEW'.
Because a View is a database structural object, it is removed from the database schema using the DDL command 'DROP VIEW'.
This question belongs to:
Computer
Database Management System (DBMS)
Question #2
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Which of the following is a valid SQL statement to add a new column to a table?
Correct Answer: Option B
Explanation:
Both 'ADD column_name datatype' and 'ADD COLUMN column_name datatype' are valid syntax in some DBMS, but standard SQL uses 'ADD column_name datatype'. However, many DBMS support both.
Both 'ADD column_name datatype' and 'ADD COLUMN column_name datatype' are valid syntax in some DBMS, but standard SQL uses 'ADD column_name datatype'. However, many DBMS support both.
This question belongs to:
Computer
Database Management System (DBMS)
Question #3
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Which SQL command deletes all rows from a table without deleting the structural schema, cannot be rolled back easily in some systems, and does not fire delete triggers?
Correct Answer: Option A
Explanation:
TRUNCATE is a DDL command that quickly removes all records from a table by deallocating the data pages, bypassing row-level logging and triggers while leaving the table structure intact.
TRUNCATE is a DDL command that quickly removes all records from a table by deallocating the data pages, bypassing row-level logging and triggers while leaving the table structure intact.
This question belongs to:
Computer
Database Management System (DBMS)
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