Question

我编写了此查询，它的目的是向数据库中包含信息的客户发送电子邮件。我希望它检查返回为0的任何值，而不是在@message中发送它们。我想我将需要一个if语句，但是我一直无法弄清楚如何使其工作。任何帮助表示赞赏。

查询：

select @AssignedCount = (select COUNT(*)
 FROM event
 where status_name = 'ASSIGNED' AND primary_unitid = NULL
 OR status_name = 'ASSIGNED' AND primary_unitid = '')

select @UnitResource = (select COUNT (*)
from unit_resources
where unit_seqnum NOT IN (select unit_seqnum from unit))

select @UnitEmployee = (select COUNT (*)
from unit_employees
where unit_seqnum NOT IN (select unit_seqnum from unit))

select @LoggedOff = (select COUNT(*) 
from unit 
where status_name = 'LOGGED_OFF')

select @Duplicates = (SELECT ISNULL(
(select COUNT(*)
from unit
group by unitid 
having COUNT(*) > 1), 0))


select @message =


'Status Report' +
'   Events in assigned status with no primary unit: '
+ REPLACE((str(@AssignedCount)),' ','') +

' Un-linked unit resource table rows: '
+ REPLACE((str(@UnitResource)),' ','') +

' Un-linked Unit resource table rows: '
+ REPLACE((str(@UnitEmployee)),' ','') + 

'   Units with a status of Logged Off: '
+ REPLACE((str(@LoggedOff)),' ','') +

'   Duplicate Units: '
+ REPLACE((str(@Duplicates)),' ','')`

Answer 1

实际上，我个人可能会而不是一堆IF语句，而是尝试这样的事情并一次性完成：

SET @message = CONCAT('Status Report',
                      (SELECT CONCAT('   Events in assigned status with no primary unit: ',COUNT(*))
                       FROM event
                       WHERE status_name = 'ASSIGNED'
                         AND primary_unitid = NULL
                          OR status_name = 'ASSIGNED'
                         AND primary_unitid = ''
                       HAVING COUNT(*) > 0),
                      ((SELECT CONCAT(' Un-linked unit resource table rows: ',COUNT (*))
                        FROM unit_resources ur
                        WHERE NOT EXISTS (SELECT 1 --I changed this from a NOT IN to an EXISTS, as NOT in have behave oddly with NULLs
                                          FROM unit u
                                          WHERE u.unit_seqnum = ur.seqnum)
                        HAVING COUNT(*) > 0))); --You get the idea now

这里我还没有做很多事情，但是HAVING COUNT(*) > 0意味着当没有相关行时，将不返回任何行（包括0）。这意味着信息不会与@message的值连接。

Answer 2

您将必须使用if语句来动态构建字符串：

-- setting to blank; otherwise, the string would be null
set @message = ''

-- dynamically building @message with if statements
if @AssignedCount > 0
    set @message =  'Status Report' +
                    '   Events in assigned status with no primary unit: '
                    + REPLACE((str(@AssignedCount)),' ','')

if @UnitResource > 0
    set @message = @message + ' Un-linked unit resource table rows: '
                            + REPLACE((str(@UnitResource)),' ','')

if @UnitEmployee > 0
    set @message = @message + ' Un-linked Unit resource table rows: '
                            + REPLACE((str(@UnitEmployee)),' ','')

if @LoggedOff > 0
    set @message = @message + '   Units with a status of Logged Off: '
                            + REPLACE((str(@LoggedOff)),' ','')

if @Duplicates > 0
    set @message = @message + '   Duplicate Units: '
                            + REPLACE((str(@Duplicates)),' ','')

-- removing leading space from @message if AssignedCount is 0
set @message = ltrim(@message)

如果为假，则忽略某些行

2 个答案: