In databases, primary keys are oftenset to auto-incrementso that new rows automatically receive unique values. However,one common error is manually inserting a value into an auto-incremented primary key column, whichoverrides the automatic numberingand may cause conflicts.

Example of Auto-Increment Setup:

sql

CREATE TABLE Users (

UserID INT AUTO_INCREMENT PRIMARY KEY,

Username VARCHAR(50)

);

Incorrect Insert (Error-Prone Approach):

sql

INSERT INTO Users (UserID, Username) VALUES (100, 'Alice');

Thismanually overrides the auto-increment, which can lead toduplicate key errors.

Correct Insert (Avoiding Errors):

sql

INSERT INTO Users (Username) VALUES ('Alice');

Thedatabase assigns UserID automatically, preventing conflicts.

Why Other Options Are Incorrect:

Option B (Failing to set a numeric value) (Incorrect):The databaseautomatically assignsvalues when AUTO_INCREMENT is used.

Option C (Designating multiple primary keys) (Incorrect):Whileincorrect, most databases will prevent this at creation time.

Option D (Forgetting to specify which is the auto-increment column) (Incorrect):If AUTO_INCREMENT is set, the database handles numbering automatically.

Thus, the most common error isInserting a value and overriding auto-increment, which can causeduplicate key errors and data inconsistencies.