When primary key is made up of two or more columns then it is called composite primary key. So why cant there be multiple primary key in a table? 20th question.
A table can only ever have a one primary key. It is not possible to create a table with two different primary keys. You can create a table with two different unique indexes (which are much like a primary key) but only one primary key can exist.
A table can only have one primary key to ensure each row is unique. If multiple columns are needed to ensure uniqueness, they form a composite primary key. Multiple primary keys would create ambiguity, but a composite key maintains the rule of a single primary key while ensuring uniqueness.
When primary key is made up of two or more columns then it is called composite primary key. So why cant there be multiple primary key in a table? 20th question.
A table can only ever have a one primary key. It is not possible to create a table with two different primary keys. You can create a table with two different unique indexes (which are much like a primary key) but only one primary key can exist.
There is only one primary key
and primary key itself is unique
Normally there should be only one primary key in a table. But if u want 2 then there are options to make 2 primary keys. Both should be unique as well
You are wrong
A table can only have one primary key to ensure each row is unique. If multiple columns are needed to ensure uniqueness, they form a composite primary key. Multiple primary keys would create ambiguity, but a composite key maintains the rule of a single primary key while ensuring uniqueness.