Primary key versus key

key, mysql, primary-key

Solution

Yes, the `KEY` keyword is just an alias for the `INDEX` keyword.

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
  ...
  {INDEX|KEY} [index_name] [index_type] (index_col_name,...)
      [index_option] ...

Source: MySQL Documentation: CREATE TABLE

Problem

When creating a mysql dump containing the structure of my database, one of the tables shows the following: ``` CREATE TABLE `completedTransactions` ( `paymentId` int(10) unsigned NOT NULL, `timestamp` int(15) unsigned NOT NULL, `actionTaken` varchar(25) NOT NULL, `response` varchar(255) NOT NULL, `responseCode` int(5) NOT NULL, PRIMARY KEY (`paymentId`,`timestamp`), KEY `paymentId` (`paymentId`), ``` The primary key is what I was expecting, but I'm unsure what the last line is about? ``` KEY `paymentId` (`paymentId`), ``` Is this related to an index?

Original source