How to count the number of record bars when using group by Count DISTINCT

For example such a table, I would like to count the number of records for which email and passwords are not the same

Copy the Code code as follows:

CREATE TABLE IF not EXISTS ' test_users ' (
' email_id ' int (one) unsigned not NULL auto_increment,
' Email ' char (+) not NULL,
' Passwords ' char (+) is not NULL,
PRIMARY KEY (' email_id ')
) Engine=myisam DEFAULT Charset=utf8 auto_increment=6;

INSERT into ' test_users ' (' email_id ', ' email ', ' passwords ') VALUES
(1, ' jims@gmail.com ', ' 1e48c4420b7073bc11916c6c1de226bb '),
(2, ' jims@yahoo.com.cn ', ' 5294cef9f1bf1858ce9d7fdb62240546′ '),
(3, ' default@gmail.com ', ' 5294cef9f1bf1858ce9d7fdb62240546′ '),
(4, ' jims@gmail.com ', "),
(5, ' jims@gmail.com ', ");
That's what we're usually doing.

Copy the Code code as follows:

SELECT COUNT (*) from test_users WHERE 1 = 1 GROUP by email,passwords

What is the result of this?

Copy the Code code as follows:

COUNT (*)
1
2
1
1

Obviously this is not the result I want, so the statistics are the same email and passwords the number of records of the sum of the following so that it can be

Copy the Code code as follows:

SELECT COUNT (DISTINCT email,passwords) from ' test_users ' WHERE 1 = 1

Of course, in PHP can also use mysql_num_rows to get the number of records, but this is not high efficiency, you can refer to this article
Mysql_num_rows VS COUNT Efficiency problem analysis

The above describes how to use group by when counting the number of records count DISTINCT, including the aspects of the content, I hope the PHP tutorial interested in a friend helpful.

