Can we have more than one primary key in table

Pramod Gupta

7y1.5kSQL

can we have more than one primary key in table

15 Replies

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Udit Chauhan7y ago
No, we can not have more than one primary key in table.

if you want to make uniqueness of records then you can make multiple columns together as composite key.
Purvi Barot7y ago
A primary key is a field in a table which uniquely identifies each row/record in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values.

A table can have only one primary key, which may consist of single or multiple fields. When multiple fields are used as a primary key, they are called a composite key.

If a table has a primary key defined on any field(s), then you cannot have two records having the same value of that field(s).

Thank you!
Shahriar Nikkhah7y ago
You can creat 2 UNIQUE KEYs, each UK and have multiple fields
Jenith Thakkar7y ago
Primary Key:
There can only be one primary key in a table
In some DBMS it cannot be NULL - e.g. MySQL adds NOT NULL
Primary Key is a unique key identifier of the record

Unique Key:
Can be more than one unique key in one table
Unique key can have NULL values
It can be a candidate key
Unique key can be NULL and may not be unique
Code Alone7y ago
In RDBMS you can't create multiple primary key. There are no Word like "Primary Keys". You can create a Primary Key only by one or more field/s.
As per Your situation You have multiple Primary Key on table, then you can use Unique Key by uncheck the Allow Nulls. It will work like primary key. They can be created multiple . For more knowledge about keys you can refer below articles :
https://www.c-sharpcorner.com/article/find-primary-unique-foreign-keys-and-delete-them/
https://www.c-sharpcorner.com/article/add-primaryuniqueforeign-keys-and-delete-them-in-sql/
Faisal Pathan7y ago
No, we can not create.
normally when we are new to RDBMS are often to get confused with the restriction of single Primary Key in table
here we can use concept of Composite Key.
1. If the Primary Key is defined using more that one columns,Its call Composite Key or Composite Primary Key.
Md Sarfaraj7y ago
You can not uses

Vinay Kumar Dara7y ago

No ! but as a combination of two columns we called Composite key.

Student Table: As a combination of RollNo and Branch columns only Student table can get the result.

RollNo	Branch	Rank#
1	ECE	22
2	ECE	4
1	CSE	12

Salman Beg7y ago
No, We can not create more than one primary key in a table.
Rajeesh Menoth7y ago
Hi,

Only one !! The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values.

Reference :

https://www.w3schools.com/sql/sql_primarykey.asp
Kalyani Shevale7y ago
A table can have only one primary key, which may consist of single or multiplefields. When multiple fields are used as a primary key, they are called a compositekey. If a table has a primary key defined on any field(s), then you cannot have two records having the same value of that field(s).
Ravi Patel7y ago
A table can have only one primary key, which may consist of single or multiplefields. When multiple fields are used as a primary key, they are called a compositekey
Jignesh Kumar7y ago
@Amit Gupta, We can create for multiple column but pk will be only one. We can not create more than one primary key per Table.
Amit Gupta7y ago
Yes definitely, select the columns in the designer that you want to make primary key -> right click -> primary key. That's it
Jignesh Kumar7y ago
Hi Pramod,

No we can not create more than one primary key for table. Only one PK for table.