按第一个字符分组 [英] group by first character

问题描述

我在Oracle SQL中有一个查询问题。

I have a problem with a query in Oracle SQL.

我在 first_name 列中有一个员工表。我想根据 first_name 中的第一个字符对记录进行分组。

I have a first_name column in an employees table. I want to group my records according to the first character in first_name.

例如，我有26条记录，一个带有 name ='Alice'的名字，一个带有 name ='Bob'的名字，依此类推名字的第一个字符。查询后，应该有26个组，每个组一个员工。

For example, I have 26 records, one with name = 'Alice', one with name = 'Bob', and so on down the alphabet for each name's first character. After the query, there should be 26 groups with one employee each.

我尝试了以下操作，但没有用：

I tried the following, but it's not working:

SELECT employee_id, (SUBSTR(first_name,1,1)) AS alpha FROM employees
GROUP BY alpha;

name_which_starts_from       employees  
A                            10  
B                            2  
C                            4  
D                            9  
E                            3  
G                            3  
H                            3  
I                            2  
J                            16  
K                            7  
L                            6  
M                            6  
N                            4  
O                            1  
P                            6  
R                            3  
S                            13  
T                            4  
V                            2  
W                            3  

推荐答案

您的查询是错误的，因为如果您想使之工作，则需要对EMPLOYEE_ID执行一些聚合功能。

Your query is wrong, since you would need to perform some aggregation function on EMPLOYEE_ID if you want that to work.

像：

select substr(first_name,1,1) as alpha, count(employee_id)
  from employees
 group by substr(first_name,1,1)

您到底想完成什么？

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