[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Y] names . [See identifiers] normalization Boyce-Codd normal form (BCNF) 2nd defined 2nd first normal form (1NF) 2nd 3rd 4th 5th second normal form (2NF) 2nd 3rd 4th 5th third normal form (3NF) 2nd 3rd 4th 5th 6th NOT NULL table creation NOT operator now() function NULL value comparison operators 2nd 3rd table creation NULL values database design 2nd numeric functions 2nd 3rd 4th 5th 6th numerical columns 2nd Decimale DOUBLE type FLOAT type INT type Numeric type |