All the keys which are not primary key are called an Alternate Key. Example: In this table, StudID, Roll No, Email are qualified to become a primary key. But since StudID is the primary key, Roll No, Email becomes the alternative key.
What is Alternate key in computer science?
An alternate key (Alt key) is a key that is present on most computer keyboards and is considered a modifier key that can used similarly to the shift or control keys. In other words, the alternate key provides alternate input and operations when pressed in combination with other keys.
What is Alternate key in simple words?
In simple words, you can say that any of the candidate key which is not part of primary key is called an alternate key. So when we talk about alternate key, the column may not be primary key but still it is a unique key in the column.
What is an Alternate key Class 10?
If any table have more than one candidate key, then after choosing primary key from those candidate key, rest of candidate keys are known as an alternate key of that table.
How do you use alternate keys?
Rules for Alternate Key
- The alternate key is a part of a candidate key but not a part of the primary key.
- Defined by “UNIQUE”.
- Alternate keys values should be unique.
- If a table consists of only one candidate key, then it becomes the primary key; there will be no alternate key.
What do you understand by alternate keys in a table give a suitable example from a table?
Alternate key: the Alternate key is a key that can be work as a primary key. Basically, it is a candidate key that currently is not the primary key. Example: In below table AdmissionNo becomes Alternate Keys when we define RegistrationNo as Primary Key.
How do I use alternate keys on my keyboard?
To type the alternate character on a key, press the right Alt key and the desired key. For example, type Alt + E to type € on a French or German keyboard. note: The right Alt key, might also be Alt Gr or Alt Car depending on your location.
Why is an alternate key?
Alternate keys are those Candidate keys that were not chosen to be the Primary key of the table. Composite key is a Candidate key that consists of more than one attribute. Foreign key is an attribute which is a Primary key in its parent table but is included as an attribute in the host table.
What is an alternate key constraint?
An alternate key is a key associated with one or more columns whose values uniquely identify every row in the table, but which is not the primary key. Each alternate key can generate a unique index or a unique constraint in a target database.
What is alternate key for?
An alternate key is none other than a candidate key, so the use/role of an alternate key is the same. It means an alternate key is also used to identify those columns in a table that can uniquely identify all the records of the table.
What is the difference between primary key and alternate key?
Primary key is a Candidate key chosen to uniquely identify tuples in the table. Primary key values should be unique and non-null. Alternate keys are those Candidate keys that were not chosen to be the Primary key of the table. Composite key is a Candidate key that consists of more than one attribute.
Can alternate key have NULL values?
There can be one or more alternate keys in a table and contain NULL values unless it is mentioned to be NOT NULL explicitly. The UNIQUE keyword is used to define the alternate key, which indicates the value must be unique.
