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|MySQL: Primar y key, index, unique|
what is what?
In MySQL - what is a "primary keys"?
Is it one column in a table?
Can it be more than one column?
Is it the same as an Index?
Does a table HAVE to have a primary key?
|Is it one column in a table? |
It can be one or more.
|Is it the same as an Index? |
No, a primary key uniquely identifies each individual row in a table. An index improves the speed of operations on a table, it can also be on one or more columns.
|Does a table HAVE to have a primary key? |
No, but it is good practice IMHO.
Thanks for posting, bad one - and thanks for your straight answers. Kudos.
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