Question

我需要做的是创建一个select语句，输出表中字段中第一个字符的总和，使输出看起来像

A,12
B,0
C,20
D,14
E,0
ect...

该表被称为联系人，在上面有12个人的名字以字母A开头，并且出现了0个字母B.

我希望我已经正确解释了

Answer 1

试试这个：

select substr(name, 1,1), count(*) from contacts group by substr(name, 1,1)

Answer 2

你可以这样做

select 
left(UPPER(firstname),1) as initial , 
count(*) as tot from users 
group by initial ;

UPDATE因为你想要显示列表中不存在的字符，你可能还需要一个查找表，然后加入查找表。查找表只有字母

select 
a.alpha,
coalesce(b.tot,0)  as total
from alphabets a
left join
(
  select
  left(UPPER(firstname),1) as initial , 
  count(*) as tot from users 
  group by initial
)b
on b.initial = a.alpha
;

OR

select 
a.alpha,
count(u.firstname) as tot
from 
alphabets a 
left join users u on a.alpha = left(UPPER(u.firstname),1)
group by a.alpha

<强> DEMO

Answer 3

希望这会有所帮助。

SELECT LEFT(firstname,1) as character, COUNT(1) as totalCount 
FROM contacts
GROUP BY initial ORDER BY firstname;

Answer 4

为了使结果显示缺失的字母，您需要手动生成所有字母（例如，使用子查询）

SELECT  a.Letter, 
        COUNT(u.Name) AS TotalCount
FROM
        (
            SELECT 'A' Letter UNION ALL
            SELECT 'B' Letter UNION ALL
            SELECT 'C' Letter UNION ALL
            -- until Z
            SELECT 'Z' Letter 
        ) AS a
        LEFT JOIN userList u
            ON a.Letter = LEFT(u.Name, 1)   -- <== column name
GROUP   BY a.Letter
ORDER   BY a.Letter

Answer 5

艰难之路

  SELECT
 'A' as letter , 
  count(*) as total FROM totalCount
  WHERE left(UPPER(firstname),1)='A'
  UNION
  SELECT
  'B' as letter , 
  count(*) as total FROM totalCount
  WHERE left(UPPER(firstname),1)='B'
  .....
  UNION
  SELECT
  'Z' as letter , 
  count(*) as total FROM totalCount
  WHERE left(UPPER(firstname),1)='Z'

Answer 6

创建另一个表

table_letter
id letter
1    A
2    B
3    C
...
26   Z

SELECT a.letter, COUNT(b.name) as total
FROM table_letter a
LEFT JOIN contacts b
ON a.letter = left(UPPER(b.name),1)
GROUP BY a.letter

mysql选择第一个字母字符的出现总和

6 个答案: