Which of the following is the correct syntax to add a NOT NULL constraint to a column named email in SQL?

easy📝 Syntax Q12 of 15

SQL - Table Constraints

Which of the following is the correct syntax to add a NOT NULL constraint to a column named email in SQL?

AALTER TABLE users ALTER COLUMN email SET NOT NULL;

BALTER TABLE users ADD CONSTRAINT email NOT NULL;

CALTER TABLE users MODIFY email NOT NULL;

DALTER TABLE users CHANGE email TO NOT NULL;

Step-by-Step Solution

Solution:

Step 1: Recall SQL syntax for NOT NULL constraint
To set a column NOT NULL, the standard syntax is ALTER TABLE table ALTER COLUMN column SET NOT NULL.
Step 2: Match syntax with options
ALTER TABLE users ALTER COLUMN email SET NOT NULL; matches the correct syntax. Options A, B, and D use incorrect or invalid syntax.
Final Answer:
ALTER TABLE users ALTER COLUMN email SET NOT NULL; -> Option A
Quick Check:
ALTER COLUMN ... SET NOT NULL = Correct syntax [OK]

Quick Trick: Use ALTER COLUMN ... SET NOT NULL to add NOT NULL [OK]

Common Mistakes:

MISTAKES

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