In depth analysis of the differences between SUM and COUNT in SQL statements

SUM is the sum of the numeric columns of eligible records

COUNT is the number of qualified results (or records) in a query

Such as:

Table fruit

id name price

1 apple 3.00

2 pear 4.00

select count (price) from fruit; -- the result after execution is: 2 (indicating that there are 2 records)

select sum (price) from fruit; -- the result after execution is: 7:00 (indicating that the sum of the price fields of each record is 7.00)