Sql primary key

/* A primary key allows each record in a table to be uniquely identified. There can only be one
primary key per table, and you can assign this constraint to any single or combination of columns.
However, this means each value within this column(s) must be unique.
Typically in a table, the primary key is an ID column, and is usually paired with the AUTO_
INCREMENT keyword. This means the value increases automatically as new records are created. */
CREATE TABLE stats(id INT NOT NULL PRIMARY KEY, name TEXT)

Change primary key sql

ALTER TABLE <Table_Name>
DROP CONSTRAINT <constraint_name>

ALTER TABLE <Table_Name>
ADD CONSTRAINT <constraint_name> PRIMARY KEY (<Column1>,<Column2>)

Source: stackoverflow.com

Primary key sql

CREATE TABLE student

(

Roll integer (15) NOT NULL PRIMARY KEY,

Name varchar (255),

Class varchar (255),

Contact No varchar (255),

);

Source: wlearnsmart.com

Primary key in sql

Primary Key :
It is unique column in every table in a database
It can ONLY accept;
    - nonduplicate values
    - cannot be NULL

Primary key in sql

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