The document defines and describes different types of keys used in database management systems. It explains that a primary key uniquely identifies each row in a table and cannot contain null values or duplicate values. A candidate key can also uniquely identify rows but other attributes can also qualify. An alternate key is like a primary key but a table can only have one primary key while other candidate keys are alternate keys. A composite key contains two or more columns that together uniquely identify each row. A super key can identify rows but may contain extra attributes, allowing null values. A foreign key points to the primary key in another table to link the tables.

1. KEYSINDBMS
PRESENTED BY,
KANTA ANURAG SHAOO : -220301120178

2. Keys
Primary Key
Composite
Key
Super Key
Foreign Key
Candidate Key
Alternate Key
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3. Primary key:-
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 A primary key is the column or columns that contain values that uniquely identify each row in a table.
 The value of a primary key can’t be null.
 It should not allowed duplicate value

4. Candidate key:-
A candidate key is an attribute or set of attributes that can uniquely
identify a tuple(A tuple in DBMS is a collection of attribute values in which
no two unique items have the same name.).
Except for the primary key, the remaining attributes are considered a
candidate key.
 The candidate keys are as strong as the primary key

5. Alternate key:-
 It is a column or group of columns that uniquely identify every row in a table.
 A table can have multiple choices for a primary key but only one can be set as primary key
and rest are known as alternate key.

6. Composite key:-
 A composite key is a candidate key that consists of two or more attributes (table
columns) that together uniquely identify an entity occurrence (table row).
 Overall, composite keys are an important concept in database design and can be
used to ensure data integrity and create relationships between tables.

7. Super key:-
 In the context of databases, a super key is a set of one or more attributes or
columns in a table that can uniquely identify each row in that table.
 Unlike a primary key, a super key may not be minimal, meaning it may contain
additional attributes beyond those necessary to uniquely identify each row.
 It support null value.

8. Foreign key:-
 Foreign key are the column of an a table used to point to the primary
key.
 Foreign keys allow key values that are all NULL.

9. Thank you