Question

Differentiate between:

a. CHAR and VARCHAR datatypes

b. Foreign Key and Composite Key​

Answer 1

Answer:

ChaR AND VARCHAR:- VARCHAR is variable length, while CHAR is fixed length. CHAR is a fixed length string data type, so any remaining space in the field is padded with blanks. CHAR takes up 1 byte per character. ... VARCHAR is a variable length string data type, so it holds only the characters you assign to it.

Explanation:

Foreign Key and Composite Key:-

Composite key is a Candidate key that consists of more than one attribute. Foreign key is an attribute which is a Primary key in its parent table but is included as an attribute in the host table. Foreign keys may accept non-unique and null values.

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