添加查询结果

Question

我有这个问题：

select 
sum(if(idcasa = 254, gcasa, 0)) as casa,  
sum(if(idvisitante = 254, gvisitante, 0)) as visitante
from partido
where  idcasa = 254 or idvisitante = 254 and  idpais = 1 and idtemporada = 1 and idcategoria = 1;

我想要的是添加结果，如下所示：

sum(casa + visitante) as goles

Answer 1

我怀疑这是你想要的查询：

select sum(case when idcasa = 254 then gcasa else 0 end) as casa,  
       sum(case when idvisitante = 254 then gvisitante else 0 end) as visitante,
       sum(case when idcasa = 254 then gcasa else gvisitante end) as total
from partido
where (idcasa = 254 or idvisitante = 254) and
      idpais = 1 and
      idtemporada = 1 and
      idcategoria = 1;

首先，请注意对where子句的更改 - 括号。我猜这是你真正想要的逻辑。

其次，只需在表达式中添加值即可。您可以使用子查询首先定义值，然后添加它们，但表达式很简单。并且，子查询通常会在MySQL中产生性能开销。

第三，我将if替换为case。后者是条件表达式的ANSI标准。

Answer 2

WITH temp AS ( select sum(if(idcasa = 254, gcasa, 0)) as casa,
sum(if(idvisitante = 254, gvisitante, 0)) as visitante from partido where idcasa = 254 or idvisitante = 254 and idpais = 1 and idtemporada = 1 and idcategoria = 1 ) SELECT sum(casa + visitante) as goles FROM temp;