不能在 WHERE 子句中使用来自 SELECT 子句的别名

Question

使用stormtrooper_java；

SELECT imperial_battlegroup.BGID, imperial_battlegroup.Designation, imperial_battlegroup.HQ_LocationX, imperial_battlegroup.HQ_LocationY,
stormtrooper_unit.STUID, stormtrooper_unit.UnitCmd, stormtrooper_unit.UnitType, stormtrooper_unit.Location_X, stormtrooper_unit.Location_Y,
ABS(stormtrooper_unit.Location_X - stormtrooper_unit.Location_Y) AS XYRange 
from imperial_battlegroup inner join
     stormtrooper_unit
     on imperial_battlegroup.BGID = stormtrooper_unit.UnitCmd
WHERE Designation = 'Battle Group I' and UnitType = 'Aslt Infantry' AND 
      XYRange > 100;

当我在没有 XYRange > 100 的情况下执行文件时，它工作得很好，但我确实需要查询中的过滤逻辑。

如何调整我的查询以根据此计算条件过滤结果？

Answer 1

试试这个：

SELECT imperial_battlegroup.BGID, imperial_battlegroup.Designation, 
imperial_battlegroup.HQ_LocationX, imperial_battlegroup.HQ_LocationY,
stormtrooper_unit.STUID, stormtrooper_unit.UnitCmd, 
stormtrooper_unit.UnitType, stormtrooper_unit.Location_X, 
stormtrooper_unit.Location_Y,
ABS(stormtrooper_unit.Location_X - stormtrooper_unit.Location_Y) AS XYRange 
from imperial_battlegroup inner join
stormtrooper_unit
on imperial_battlegroup.BGID = stormtrooper_unit.UnitCmd 
WHERE Designation = 'Battle Group I' and UnitType = 'Aslt Infantry' AND 
ABS(stormtrooper_unit.Location_X - stormtrooper_unit.Location_Y) > 100;

刚刚更新了最后一行，其余一切都一样。

Answer 2

SQL 不允许您在 WHERE 子句中使用列别名。它确实扩展了 HAVING，因此一种解决方案是：

SELECT bg.BGID, bg.Designation, imperial_battlegroup.HQ_LocationX, bg.HQ_LocationY,
        u.STUID, u.UnitCmd, u.UnitType, u.Location_X, u.Location_Y,
ABS(stormtrooper_unit.Location_X - stormtrooper_unit.Location_Y) AS XYRange 
from imperial_battlegroup bg inner join
     stormtrooper_unit
     on bg.BGID = u.UnitCmd
WHERE Designation = 'Battle Group I' and UnitType = 'Aslt Infantry' 
HAVING XYRange > 100;

另一种选择是重复WHERE中的表达式。

Answer 3

禁止在where子句中使用别名。所以使用函数本身

where ABS(stormtrooper_unit.Location_X - stormtrooper_unit.Location_Y)> 100

不能在 WHERE 子句中使用来自 SELECT 子句的别名

Cannot use alias from SELECT clause in the WHERE clause

mysql

sql

filtering

where-clause

column-alias