Answer
Constraints like primary key, foreign key, unique, check, not null, and default rules ensure accurate, valid, and reliable data.
Quick Answer
Constraints are rules you enforce at the database level. Common ones: NOT NULL (column can't be empty), UNIQUE (no duplicates), CHECK (value must meet a condition), DEFAULT (fallback value), PRIMARY KEY, and FOREIGN KEY. They catch bad data before it ever lands in the table.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ