SQL查询-选择用户名并汇总其行

Question

I have this query

SELECT username FROM paymentValue

I can sum paymentValue for username like

SELECT username, SUM(paymentValue) WHERE username = 'john'

But how to select sums for all usernames to get return like: john, 146 marry, 3456 anna, 2043

Answer 1

use the 'group by' clause

select username, sum(paymentvalue) as sumofpayments from thetable
group by username

Answer 2

SELECT username, SUM(paymentValue) 
FROM TableName
GROUP BY username

to JOIN with another table

SELECT username, SUM(paymentValue) 
FROM TableName INNER JOIN SecondTable
ON TableName.RefrencingColumn = SecondTable.RefrencingColumn  
WHERE username = 'john'
GROUP BY username

Answer 3

select username,
       sum(paymentValue) as Payments
from paymentValue
group by username