Question

我有一个带有非唯一名称字段的MySql表，我想查询以下内容;

对于每个名称值（“John”）计算有多少条记录（32条记录名为John），我最终会将其写入每条记录。

平均每个名称组的计数（例如，带有John的32个记录和带有Sally的42个记录，表37记录的平均值）

计数计数含义，例如6个记录组，10个20记录组等

我可以使用一个或多个查询执行此操作吗？

Answer 1

SELECT 
  AVG(ct) 
FROM (
  SELECT 
    COUNT(name) as ct 
  FROM 
    names 
  GROUP BY  
    name) as temp1;

每次点票数http://sqlfiddle.com/#!2/b0628/1：

SELECT 
  COUNT(ct) AS "Count_per_count",
  ct as "Actual Count" 
FROM (
  SELECT 
    COUNT(name) as ct 
  FROM 
    names 
  GROUP BY 
    name) as temp1 
GROUP BY ct;

Answer 2

select name, count(*) as num from table group by name;

select ((select count(*) from table) / (select count(distinct name) from table));

select count(*) as num, type from
    (select count(*) as type from table group by name) t
group by type

计算相似记录的数量，平均计数和具有特定计数的＃

2 个答案: