What is the difference between UNIQUE and DISTINCT keywords in DBMS?
First we declare is as primary key and after group by we can get uniqu values.
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (ID)
);
SELECT ID, LastName,FirstName
FROM Persons
GROUP BY ID, LastName,FirstName;
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