primary key: IT IS THE MAIN KEY AND IT DOES NOT ALLOWS THE NUL

what is primary key,unique key, foreign key? can u teach me
in simple language?

Question Posted / uma maheswari

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Answer Posted / uma maheswari

primary key:
IT IS THE MAIN KEY AND IT DOES NOT ALLOWS THE NULL VALUE...
Unique key:
IT IS SIMILAR TO PRIMARY KEY .IT ALSO DONT ALLOWS THE NULL VALUE.
foreign key:
IT IS USED TO REPRESENT THE PRIMARY KEY VALUE...

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