1 ifnull
ifnull(a,b)函数解释:
如果value1非空,结果返回a,否则返回b
select ifNull(50,null) as SecondHighestSalary; 这样最后生成了一个表,列名是SecondHighestSalary
1 ifnull
ifnull(a,b)函数解释:
如果value1非空,结果返回a,否则返回b
select ifNull(50,null) as SecondHighestSalary; 这样最后生成了一个表,列名是SecondHighestSalary