Question

a) identify the primary key of the Book Table, also mention the suitable reason for choosing it as a primary key .

b) difference between:
i. char and varchar data type
ii. DDL and DML

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Answer 1

a) the primary key of the table is book id as it can not be same in any case.

b) char denotes character. it means it stores character.

it holds 255 characters.

WHILE

varchar dented variable character. it means it stores variable characters.

ii. DDL stands for data definition language.

it's commands are:

-CREATE

-ALTER

-DROP

while

DML stands for data manipulation language. it's commands are:

-SELECT

-INSERT

-UPDATE

-DELETE