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What does the KEY keyword mean in MySQL?
Key is synonymous to an index. If you want to create an index for a column, then use ‘Key’.
As stated in the official docs:
KEY is normally a synonym for INDEX. The key attribute PRIMARY KEY can also be specified as just KEY when given in a column definition. This was implemented for compatibility with other database systems.
The key can be used with Primary Key:
Let us first create a table. Here is the query to set primary key for a column “id”.
mysql> create table KeyDemo
-> (
-> id int,
-> primary key(id)
-> );
Query OK, 0 rows affected (0.55 sec)
Inserting two records.
mysql> insert into KeyDemo values(1); Query OK, 1 row affected (0.12 sec) mysql> insert into KeyDemo values(2); Query OK, 1 row affected (0.14 sec)
To display all the records.
mysql> select *from KeyDemo;
Here is the output.
+----+ | id | +----+ | 1 | | 2 | +----+ 2 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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