The multi-part identifier could not be bound sql where clause - sql

Question

I am trying to multiply two tables using the code below to get a new calculated column. I am using the SQL Server Express Edition and SQL Server Management Studio.
select
[Yield_unpiv].[SubPrecinct],
[Yield_unpiv].[LandUse],
[Yield_unpiv].[Yield] * [LU_Rules_Final].[AM_GenRateFinal] * [LU_Rules_Final].[AM_In_factor] / [LU_Rules_Final].[UnitValue] as AM_In
from
Yield_unpiv, LU_Rules_Final
where
[Yield_unpiv].[LandUse]=[LU_Rules_Final].[LandUse]
However, I get the following error
The multi-part identifier "Yield_unpiv.LandUse" could not be bound.
The Yield_unpiv is set up like this:
SubPrecinct | Yield | LandUse
P1 Unique #s LDResi
P1 MDResi
. .
. .
. .
P2 LDResi
P2 MDResi
. .
. .
. .
And the LU_Rules_Final is set up like this:
LandUse | UnitValue | AM_GenRateFinal | AM_In_factor
LDResi 1 2.5 0.5
BulkyGoods 100 7 0.7
MDREsi 1 0.52 0.1
.
.
.
Not sure why I am getting this multi-part identifier "Yield_unpiv.LandUse" could not be bound error.
Please help!

Answer 1

I don't know the exact cause of your error, but it likely has to do with that the column LandUse appears in both tables. I speculate that refactoring it to use explicit joins would fix the problem:
SELECT
t1.[SubPrecinct],
t1.[LandUse],
t1.[Yield] * t2.[AM_GenRateFinal] * t2.[AM_In_factor] / t2.[UnitValue] AS AM_In
FROM Yield_unpiv t1
INNER JOIN LU_Rules_Final t2
OM t1.[LandUse] = t2.[LandUse];
If this fixes your problem, then it means one more reason not to use the archaic pre ANSI-92 style of SQL joins. Always use explicit joins whenever possible.