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26 lip 2022 · A Foreign Key can’t be an Alternate Key as it is only used to reference another table. The alternate Key should be unique. An Alternate Key can be a set of a single attribute or multiple attributes. It can be NULL as well. In this article, we are going to see how to create an ALTERNATE Key in SQL using sample tables as shown.
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28 sie 2024 · An alternate key (also known as secondary key) is a column or a combination of columns in a table that can uniquely identify each row, but is not the primary key. In other words, it is an alternative to the primary key that could have been chosen as the primary key but wasn’t.
SQL Alternate Keys in a database table are candidate keys that are not currently selected as a primary key. They can be used to uniquely identify a tuple (or a record) in a table.
When a query is performed on a table that has an alternate key, the DBMS uses the alternate keys to help locate the relevant records. The alternate key is indexed in much the same way as a primary key, allowing for efficient lookup and retrieval of data.
20 sie 2019 · Candidate keys are SID or FNAME+LAME. Primary Key: SID. Alternate Key: FNAME+LAME. now with some explanation. Candidate Keys are those keys which is candidate for primary key of a table. simply all columns which full fill all the requirements of primary key.
ALTERNATE KEY is a candidate key which consists of one or more columns used to identify each row uniquely which is not treated as a Primary key. If a table contain many candidate keys among them one is treated as Primary key rest of all are called as Alternate keys.
In SQL, an alternate key is any candidate key of the table that is not designated as the primary but still allows one to uniquely identify records. Though a primary key is primarily a unique identifier for a table, alternate keys also play an extremely important role in maintaining integrity and aiding the optimization of queries.
