Mysql distinct usage-how to filter non-duplicate data in mysql

Mysql distinct usage-when using mysql to filter out non-duplicate data, you sometimes need to query records with no repeated fields, although mysql provides the keyword distinct to filter out redundant duplicate records and retain only one record, it is often used to return the number of records that do not repeat, rather than returning all values that do not record duplication. The reason is that distinct can only return its target field, but cannot return other fields. Let's take a look at the example below: table id name 1 a 2 B 3 c 4 c 5 B for example, if I want to use a statement to query all the data with no duplicate names, we must use distinct to remove redundant duplicate records. Www.2cto.com select distinct name from table the result is: name a B c seems to have achieved the effect, but what do I want to get is the id value? Change the query statement: select distinct name, id from table. The result will be: id name 1 a 2 B 3 c 4 c 5 B for a long time, finally, I found a usage in the mysql manual. www.2cto.com used group_concat (distinct name) and group by name to implement the functions that I needed 5.0 to support. suddenly, the ghost machine flashed. Since the group_concat function can be used, can other functions be used? Use the count function for a try. Now the complete statement is released: select *, count (distinct name) from table group by name result: id name count (distinct name) 1 a 1 2 B 1 3 c 1 by the way, group by must be placed before order by and limit, otherwise an error will be reported... OK, author Xie chunye