别名列上的SQL具有/ where语句

Question

我正在尝试根据别名表中查询结果中给出的值来设置列的结果

select b.* from table1 a, table1 b where a.empno=99 and a.super_empno = b.empno;

Answer 1

您没有为IN语句指定一个字段。您应该具有一个字段名称，以便与select语句进行比较。看起来像WHERE field_name IN (SELECT .....)

Answer 2

您可以在hading子句中重复聚合表达式：

update autos
    set risico = 0
    where in (select leden.lidnaam, count(deelnemers.evenementnr) as AantalDeelnames
    from leden 
        full join autos on leden.lidnr = autos.lidnr
        full join deelnemers on autos.autonr = deelnemers.autonr
        group by leden.lidnaam
        having count(deelnemers.evenementnr) = 0)