What is a composite key in SQL?
A composite key is a primary key with numerous columns as in the case of a few tables a single field might not ensure unique and not null values, so a combination of multiple fields is taken as the primary key. This composite key alludes to cases where more than one column is utilized to indicate the primary key of a table.
Example:
CREATE TABLE Orders(
Ordr ID INT,
Ordr NAME nvarchar(30),
OrdrMENU nvarchar(50),
PRIMARY KEY (OrdrNAME, OrdrMENU));