Do I need a primary key?

Question

On database systems, should each table have a primary key?

For example, I have a table table1(foreignkey1,foreignkey2,attribute), for example, it this.table1does not have a primary key.

Should I define a primary key for this table, for example table1id?

Answer 1

This is a subjective question, so I hope you do not mind, I answer with some opinion :)

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Answer 2

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Composite Primary key, :

CREATE TABLE table1(
    FK1 INT,
    FK2 INT,
    ATTRIBUTE INT,
    PRIMARY KEY (FK1, FK2)
) 

1:

ALTER TABLE table_name
ADD CONSTRAINT pk_table1 PRIMARY KEY (FK1,FK2)

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