在 SQL 中通过 cast 函数转换多行

Question

我有一个 database table，其中 name、address 和 monthly account expense 作为每个月的列信息。

我想添加 month1 到 month12 数据的 accounts table 但它是 varchar 数据类型，我想将其转换为 float 数据类型，并在查询中使用逻辑表达式获取所有费用的 SUM (month 1 + month 2 +...month12) 应该大于 10,000。

但是我无法解决这个问题，因为查询不工作并且出现错误

请检查此查询并让我知道任何更改

SELECT name
      ,address
      ,CAST(([month1] + [month2]...[month12] AS float) AS 'total expense'
FROM Accounts_Table
WHERE name LIKE 'a%'
GROUP BY name, address, 'total expense'
HAVING 'total expense' > 10000

一些建议将有助于解决此问题。

Answer 1

您添加和转换 month 列的方式不正确。

此外，您将无法在声明它的同一查询的 HAVING 子句中调用 [Total Expense] 的别名。使用 SUBQUERY.

见下文。

SELECT [name]
      ,[address]
      ,[Total Expense]
FROM (
    SELECT [name]
          ,[address]
          ,CAST([month1] AS float) +
           CAST([month2] AS float) +
           CAST([month3] AS float) +
           CAST([month4] AS float) +
           CAST([month5] AS float) +
           CAST([month6] AS float) +
           CAST([month7] AS float) +
           CAST([month8] AS float) +
           CAST([month9] AS float) +
           CAST([month10] AS float) +
           CAST([month11] AS float) +
           CAST([month12] AS float) AS [Total Expense]
    FROM [Accounts_Table]
    WHERE [name] LIKE 'a%') AS [src]
GROUP BY [name]
        ,[address]
        ,[Total Expense]
HAVING [Total Expense] > 10000

Answer 2

您必须在添加之前将每个 varchar 列转换为 Float。查看解释

, (CAST( [month1] as float) + CAST([month2] as float)... CAST([month12] as Float))  AS 
   'total expense'

在 SQL 中通过 cast 函数转换多行

Converting multiple rows through cast function in SQL

sql-server

type-conversion

sqldatatypes

sql-server-2014

sql-query-store