COMPUTER SCIENCE AND ENGINEERING
SQL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Uniquely identifies any record in a table
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It is always a number
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It is always the first number
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Uniquely identifies any field in a table
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Detailed explanation-1: -A primary key is the column or columns that contain values that uniquely identify each row in a table. A database table must have a primary key for Optim to insert, update, restore, or delete data from a database table. Optim uses primary keys that are defined to the database.
Detailed explanation-2: -A primary key, also called a primary keyword, is a column in a relational database table that’s distinctive for each record. It’s a unique identifier, such as a driver’s license number, telephone number with area code or vehicle identification number (VIN). A relational database must have only one primary key.
Detailed explanation-3: -A primary key is a column of table which uniquely identifies each tuple (row) in that table.
Detailed explanation-4: -A specific choice of columns which uniquely identified rows called primary key.
Detailed explanation-5: -The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).