→ SQL – Constraints →学習を始める /ダウンロードMP3フラッシュカード

学び始める

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

SQL – Constraints