SQL - Table Constraints
Given the table
employees(id INT PRIMARY KEY, age INT CHECK (age >= 18)), what happens if you try to insert (1, 16)?Given the table employees(id INT PRIMARY KEY, age INT CHECK (age >= 18)), what happens if you try to insert (1, 16)?
medium📝 query result Q4 of 15
Step-by-Step Solution
Solution:
Step 1: Understand the CHECK constraint on age
The CHECK constraint requires age to be 18 or older.Step 2: Analyze the insert values
Inserting age 16 violates the CHECK condition, so the insert fails.Final Answer:
The insert fails due to CHECK constraint violation -> Option CQuick Check:
CHECK constraint violation causes insert failure [OK]
Quick Trick: CHECK stops invalid data that breaks rules [OK]
Common Mistakes:
MISTAKES- Ignoring CHECK and assuming insert succeeds
- Confusing PRIMARY KEY violation with CHECK violation
- Assuming NULL is inserted automatically
Master "Table Constraints" in SQL
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