Question

我有一个问题，我需要帮助，我知道问题所在，但我无法让它发挥作用。

SQL表列poci.Value的数据类型为nvarchar，我想要做的是计算在select语句中使用* 1.5获取的值。

poci.value的值是2.6，所以当我运行查询（见下文）时，我得到的结果是2.6。我只是想用* 1.5为结果添加一个计算，但这不会起作用，因为你不能像那样计算nvarchar ..

这是查询在没有尝试计算的情况下的显示方式：

SELECT poci.Value
FROM ProductionOrder po
LEFT JOIN Product p
    ON p.ProductionOrderId = po.ProductionOrderId
LEFT JOIN ProductionOrderConfiguration poc
    ON poc.ProductionOrderId = po.ProductionOrderId and poc.Valid = 1
LEFT JOIN ProductionOrderConfigurationItem poci
    ON poci.ProductionOrderConfigurationId = poc.ProductionOrderConfigurationId
WHERE p.ProductId = #ProductId# and poci.Name = 'C_UE'

我尝试将此添加到查询的开头但不起作用：

DECLARE @Calc decimal(6,2) SET @Calc = 1.5 SELECT poci.value * @Calc AS test etc. etc..

请帮助我，我真的卡在这里！

指向tabledata的链接：

http://imgur.com/a/fCoD6

Answer 1

试试这个：

SELECT CAST(poci.Value AS DECIMAL) * 1.5

等

或者：

CREATE TEMPORARY TABLE IF NOT EXISTS temp AS
SELECT poci.Value AS val
FROM [the rest of your original query];
SELECT CAST(val AS DECIMAL(6,2)) * 1.5 FROM temp;

Answer 2

您可以尝试其中一种（MSSQL）：

DECLARE @CALC AS DECIMAL(6,2);
SET @CALC=1.5;
WITH TEST_DATA AS (SELECT CAST('2.6' AS NVARCHAR) AS VALUE UNION ALL SELECT CAST('2.8' AS NVARCHAR)  UNION ALL SELECT CAST('YES' AS NVARCHAR))
SELECT VALUE
    , VALUE * @CALC AS NEW_VALUE
FROM TEST_DATA
WHERE ISNUMERIC(VALUE)>0
;

输出：

VALUE                          NEW_VALUE
------------------------------ ---------------------------------------
2.6                            3.9000
2.8                            4.2000

或者

DECLARE @CALC AS DECIMAL(6,2);
SET @CALC=1.5;
WITH TEST_DATA AS (SELECT CAST('2.6' AS NVARCHAR) AS VALUE UNION ALL SELECT CAST('2.8' AS NVARCHAR)  UNION ALL SELECT CAST('YES' AS NVARCHAR))
SELECT VALUE
    , CASE WHEN ISNUMERIC(VALUE)>0 THEN CAST( VALUE * @CALC AS NVARCHAR) ELSE VALUE END AS NEW_VALUE
FROM TEST_DATA
;

输出：

VALUE                          NEW_VALUE
------------------------------ ------------------------------
2.6                            3.9000
2.8                            4.2000
YES                            YES

坚持对SELECT语句添加计算

2 个答案: