mysql如何统计同一字段不同值的个数

SELECT count(*)
FROM user_operation_log
WHERE origin = 'iPhone';
 
SELECT count(*)
FROM user_operation_log
WHERE origin = 'Android';
 
SELECT count(*)
FROM user_operation_log
WHERE origin = 'Web';

SELECT
  count(origin = 'iPhone' OR NULL)  AS iPhone,
  count(origin = 'Android' OR NULL) AS Android,
  count(origin = 'Web' OR NULL)     AS Web
FROM user_operation_log;

SELECT
  sum(if(origin = 'iPhone', 1, 0))  AS iPhone,
  sum(if(origin = 'Android', 1, 0)) AS Android,
  sum(if(origin = 'Web', 1, 0))     AS Web
FROM user_operation_log;

SELECT
  sum(origin = 'iPhone')  AS iPhone,
  sum(origin = 'Android') AS Android,
  sum(origin = 'Web')     AS Web
FROM user_operation_log;

SELECT origin,count(*) num FROM user_operation_log GROUP BY origin;

SELECT seller_id,COUNT(*) AS `value` FROM t_order GROUP BY seller_id ;

SELECT e.e_name AS `name`,COUNT(*) AS `value` FROM t_order o JOIN t_emp e ON e.e_id=o.seller_id  GROUP BY seller_id ;