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Question		Answer
Ensures that a column cannot have a NULL value start learning		NOT NULL
Ensures that all values in a column are different start learning		UNIQUE
A combination of a NOT NULL and UNIQUE. Uniquely identifies each row in a table start learning		PRIMARY KEY [MySQL:] UserId auto_increment primary key
Uniquely identifies a row/record in another table start learning		FOREIGN KEY
Ensures that all values in a column satisfies a specific condition start learning		CHECK
Sets a default value for a column when no value is specified start learning		DEFAULT
Used to create and retrieve data from the database very quickly start learning		INDEX
It's like a declaration of default value that increments by 1 for each record. start learning		auto_increment SQLite: autoincrement

SQL – Constraints