带有where子句的SQL sum函数

Question

I am using MsSQL and I want to add some values where some conditions are met. Is it possible to use WHERE clause in the sum() function? Or is there an equivalent function to the excel SUMIF().

Answer 1

The SUM aggregate will only operate on the result set constrained by the WHERE clause.

In other words, yes, this is fine.

SELECT SUM(days)
FROM myTable
WHERE something = another

Answer 2

You could use CASE :

SELECT SUM(CASE WHEN YourCondition=1 THEN 1 ELSE 0 END)
FROM YourTable