MySQL---accumulate a column

MySQL—accumulate a column

Shaped like this

Use the variable @sumsalary:=@sumsalary+salary to accumulate, but don’t forget to initialize the variable: select @sumsalary:=0;

Let’s take an example, a MySQL topic on a certain customer network—60

According to the cumulative sum running_total of salary, running_total is the cumulative sum of salary of the first N current employees (to_date = '9999-01-01'), and so on. The specific results are shown in the following Demo. .

select emp_no,max(salary),cast((@sumsalary:=@sumsalary+max(salary)) as decimal(9,0)) as sum from salaries s
join (select @sumsalary:=0) b
where to_date="9999-01-01" 
group by emp_no;

[Note: The cast function retains the decimal point]

result: