我在MySQL运行像下面的SQL查询: select *
from (
select 2 as o,1 as t from dual
union
select 1 as o,2 as t from dual
) x
order by if((select 1),o,t);
它运作良好,但是当我使用if声明中列的相对位置,这是行不通的。 如何使用if中O
我一直在使用attoparsec写了以下分析代码: data Test = Test {
a :: Int,
b :: Int
} deriving (Show)
testParser :: Parser Test
testParser = do
a <- decimal
tab
b <- decimal
return $