如何编写 select 语句来评估多个字段以填充新字段值？

Question

我翻了一堆帖子，但没有找到适合我问题的帖子。我试过 CASE 和 IIF，但 none 似乎有效。我妻子会说我不知道如何 Google 正确。我将导出加载到 SQL Server Express 15 和 Access 16 (365) 中。我可以使用任何一个来实现我的目标。我从数据导出中导入了一个 table，其中包含以下字段：

LogonID
DeptName
CertDate
CertStatus
PastDue

我需要编写一个查询，为 Status 字段提供适当的值，其中：

If ((CertDate Is Not Null) AND (CertStatus = ‘Current’) AND (PastDue = ‘No’)) then
    Status = ‘ReadOnTime’)

If ((CertDate Is Not Null) AND (CertStatus = ‘Current’) AND (PastDue = ‘Yes’)) then
    Status = ‘ReadLate’)

If ((CertDate Is Null) AND (CertStatus = ‘Pending’) AND (PastDue = ‘Yes’)) then
    Status = ‘UnReadLate’)

其他都是空白

Answer 1

您尝试了哪些语法？我会选择

update table my_table set
Status = (case when condition1 then 'ReadOnTime' 
else when condition2 then 'ReadLate' 
else when condition2 then 'UnReadLate' 
else '' end)

Answer 2

在 SQL 服务器中，您将使用 CASE 表达式。

我使用了您示例中的字段名称，而您没有提供 table 名称，因此您必须更新示例以满足您的需要。

SELECT CASE WHEN [CertDate] IS NOT NULL
                 AND [CertStatus] = 'Current'
                 AND [PassDue] = 'No' THEN 'ReadOnTime'
            WHEN [CertDate] IS NOT NULL
                 AND [CertStatus] = 'Current'
                 AND [PassDue] = 'Yes' THEN 'ReadLate'
            WHEN [CertDate] IS NULL
                 AND [CertStatus] = 'Pending'
                 AND [PassDue] = 'Yes' THEN 'UnReadLate'
            ELSE ''
       END AS [Status]
FROM   [YourTableName];

Answer 3

这是查询在 Access SQL 中的样子 SQL。

Select
    LogonID, 
    DeptName, 
    CertDate, 
    CertStatus, 
    PastDue, 
    IIf (CertDate Is Not Null AND CertStatus = "Current" AND PastDue = "No", "ReadOnTime",
    IIf (CertDate Is Not Null AND CertStatus = "Current" AND PastDue = "Yes", "ReadLate",
    IIf (CertDate Is Null AND CertStatus = "Pending" AND PastDue = "Yes", "UnReadLate",
     ""))) As Status 
From        Table

如何编写 select 语句来评估多个字段以填充新字段值？

how do I write a select statement that will evaluate multiple fields to populate a new field value?

sql-server

ms-access-2016