Count the number of unique data in a table

Question

I have a table in a database that stores the name of each User who accessed my application in PHP. I would like to make a function that calculates the number of unique users who accessed it so far (assuming a User can access it more than once). However, I have no idea how to make this count .

Answer 1

要计算唯一身份用户的数量，您可以

SELECT COUNT(DISTINCT `column_name`) FROM `table_name`