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Editorial Team
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Asked: 2026-06-10T14:04:07+00:00

In my database I have a list of users with information about them, and

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In my database I have a list of users with information about them, and I also have a feature which allows a user to add other users to a shortlist. My user information is stored in one table with a primary key of the user id, and I have another table for the shortlist. The shortlist table is designed so that it has two columns and is basically just a list of pairs of names. So to find the shortlist for a particular user you retrieve all names from the second column where the id in the first column is a particular value.

The issue is that according to many sources such as this Should each and every table have a primary key? you should have a primary key in every table of the database.

According to this source http://www.w3schools.com/sql/sql_primarykey.asp – a primary key in one which uniquely identifies an entry in a database. So my question is:

  1. What is wrong with the table in my database? Why does it need a primary key?

  2. How should I give it a primary key? Just create a new auto-incrementing column so that each entry has a unique id? There doesn’t seem much point for this. Or would I somehow encapsulate the multiple entries that represent a shortlist into another entity in another table and link that in? I’m really confused.

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1 Answer

  1. Editorial Team

    If the rows are unique, you can have a two-column primary key, although maybe that’s database dependent. Here’s an example:

    CREATE TABLE my_table
(
col_1 int NOT NULL,
col_2 varchar(255) NOT NULL,
CONSTRAINT pk_cols12 PRIMARY KEY (col_1,col_2)
)

    If you already have the table, the example would be:

    ALTER TABLE my_table
ADD CONSTRAINT pk_cols12 PRIMARY KEY (col_1,col_2)
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