mysql - 怎么让 SELECT 1+null 等于 1

Question

怎么让

SELECT 1+null

返回的值等于 1

实际的sql可能是

-- 比如 a为1 b为null 
select `a` + `b` from `foo`;

我想的结果是最后select到的 a + b = 1

Answer 1

It works in mysql, and you can find the corresponding function in other DBs:
select a + ifnull(b, 0) from foo;

Answer 2

The correct answer upstairs, but I think from a database perspective, if an attribute needs to be able to be added and subtracted, then the default value should be set to 0 when designing the database, so that there is no need to use it. ifnul function