SQL Not Null Constraint
1.What is the purpose of NOT NULL constraint?
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A. To accept NULL values
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B. To enforce unique values
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C. To ensure a column must have a value
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D. To remove default values
To ensure a column must have a value
To ensure a column must have a value
2.Which columns can use NOT NULL?
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A. Only primary keys
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B. Only integers
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C. Any data type
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D. Only foreign keys
Any data type
Any data type
3.What happens if you insert NULL into a NOT NULL column?
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A. It inserts default
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B. It updates old value
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C. Error
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D. Skips the row
Error
Error
4.Which of the following constraints is always NOT NULL?
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A. UNIQUE
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B. PRIMARY KEY
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C. FOREIGN KEY
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D. CHECK
PRIMARY KEY
PRIMARY KEY
5.What happens to the below given code?
CREATE TABLE books (
id INT NOT NULL
);
INSERT INTO books VALUES (NULL);
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A. NULL inserted
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B. Error: NOT NULL violation
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C. ID auto-generated
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D. Default = 0
Error: NOT NULL violation
Error: NOT NULL violation