[Solved] Given the table definition:CREATE TABLE Enrollment ( student_id INT, course_id INT, enrollment_date DATE, PRIMARY KEY (student_id, course_id) );What will happen if you try to insert two rows with the... | SQL

SQL - Table Constraints

Given the table definition:

CREATE TABLE Enrollment (
  student_id INT,
  course_id INT,
  enrollment_date DATE,
  PRIMARY KEY (student_id, course_id)
);

What will happen if you try to insert two rows with the same student_id and course_id but different enrollment_date?

AThe second insert will overwrite the first row

BBoth inserts will succeed because enrollment_date is different

CThe database will create a duplicate primary key automatically

DThe second insert will fail due to primary key violation

Step-by-Step Solution

Solution:

Step 1: Understand composite primary key uniqueness
The combination of student_id and course_id must be unique for each row.
Step 2: Analyze insert behavior
Inserting a row with the same student_id and course_id violates the primary key constraint, regardless of enrollment_date.
Final Answer:
The second insert will fail due to primary key violation -> Option D
Quick Check:
Composite key enforces uniqueness = insert fails on duplicate [OK]

Quick Trick: Composite keys block duplicate combined values [OK]

Common Mistakes:

MISTAKES

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