错误转换VARCHAR到数字在SQL减查询

Question

如果我单独运行的每一行我有这个疑问

select SUM(quantity) from Sales join Document on Sales.IdDocument = Document.IdDocument where (IdTipoDocumento = 'vco' or IdTipoDocumento = 'vcr') and IdArticulo = '01-00321' and IdListaEmpresa = 1000129 
- 
(select SUM(quantity) from Sales join Document on Sales.IdDocument = Document.IdDocument where IdTipoDocumento = 'dco' and IdArticulo = '01-00321' and IdListaEmpresa = 1000129) 

，每个查询工作正常（第一次给了419，结果，第二个380），但如果我尝试运行整个事情来获得结果（419-380）它告诉我“将数据类型varchar转换为数字时出错”。

他们都应该已经是数字（数量字段是整数类型反正），所以我不知道为什么错误出来......

Answer 1

方法1：

SELECT 
(select SUM(quantity) from Sales join Document on Sales.IdDocument = Document.IdDocument 
where (IdTipoDocumento = 'vco' or IdTipoDocumento = 'vcr') and IdArticulo = '01-00321' and 
IdListaEmpresa = 1000129) 

- 
(select SUM(quantity) from Sales join Document on Sales.IdDocument = Document.IdDocument 
where IdTipoDocumento = 'dco' and IdArticulo = '01-00321' and IdListaEmpresa = 1000129) 

方法2：

SELECT SUM(SQ) 
FROM (
SELECT CASE WHEN (IdTipoDocumento = 'vco' or IdTipoDocumento = 'vcr') THEN SUM(Quantity) 
WHEN IdTipoDocumento = 'dco' THEN -1*SUM(Quantity) 
END AS SQ 
FROM Sales join Document on Sales.IdDocument = Document.IdDocument 
where (IdTipoDocumento IN ('vco', 'vcr','dco')) and IdArticulo = '01-00321' and 
IdListaEmpresa = '1000129' 
GROUP BY IdTipoDocumento) AS T1 

方法3：

SELECT SUM(CASE WHEN IdTipoDocumento IN ('vco', 'vcr') THEN Quantity ELSE -1*Quantity END) 
AS SQ 
FROM Sales join Document on Sales.IdDocument = Document.IdDocument 
where (IdTipoDocumento IN ('vco', 'vcr','dco')) and IdArticulo = '01-00321' and 
IdListaEmpresa = 1000129 

方法3A：

SELECT IdListaEmpresa, 
     SUM(CASE WHEN IdTipoDocumento IN ('vco', 'vcr') 
        THEN Quantity 
        ELSE -1*Quantity END) AS SQ 
    FROM Sales join Document on Sales.IdDocument = Document.IdDocument 
    WHERE (IdTipoDocumento IN ('vco', 'vcr','dco')) 
     AND IdArticulo = '01-00321' 
     AND IdListaEmpresa IN (1000129, 1000130, 1,2,3,4,5) 
    GROUP BY IdListaEmpresa