计算数据库中的唯一记录 [英] Count unique records in database

问题描述

这可能是一个简单的问题，但我似乎无法在这里找到答案.我编写了一个查询，可以生成电子邮件地址列表.该列表有重复的记录，所以我做了一个GROUP BY email"，这样我就可以打印出一个只有唯一值的列表.我还需要唯一电子邮件的数量，以便我的循环正常工作.我怎么得到那个号码?mysql_num_rows 给出了包括重复电子邮件在内的总数.

This is probably an easy question, but I can't seem to find the answer on here. I have written a query that yields a list of email addresses. The list has duplicate records, so I did a "GROUP BY email" so that I could print out a list of only unique values. I also need the count of unique emails so that my loop works properly. How do I get that number? mysql_num_rows is giving the total including duplicate emails.

推荐答案

尝试:

SELECT COUNT( DISTINCT( email ) ) FROM table

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