SQL 查询：使用带左连接的聚合函数时不应为 NULL 的 NULL 值

Question

我对 SQL 没有太多经验，我正在努力解决这个问题。我有 3 个表：Projects、Calculator 和 partialBilling （注意：您在我添加的代码中看到的 'calculator' 列 'k'、'l'、'm' 等是真实的……我没有给它们起那些名字……） .

查询工作正常，但我期望聚合函数（'sumofTotal' 列）的部分值作为空值返回，它们应该不为空。如果有人指出查询中的错误，我将不胜感激。

SELECT Projects.SpCall,Projects.CustName,Projects.CustNumber
,Projects.ReceiveDate,Projects.StartDate,Projects.ProjectType
,Calculator.AN,Projects.Professional,Projects.PmUserName
,Projects.AcountManager,Projects.CrmCallNum,Projects.ProjectCategory
,Projects.CallNum,Projects.ContactName,Projects.ContactPhone
,Projects.ContactEmail,Projects.HiddenNote,Projects.RowColor
, Projects.HeaderCellText,
 SUM(Calculator.K + Calculator.L + Calculator.M + Calculator.N + Calculator.AD + Calculator.AR) AS sumofTotal
 ,partialBilling.Ammount FROM Projects LEFT JOIN Calculator ON Projects.SpCall=Calculator.AQ
  LEFT JOIN partialBilling ON Projects.SpCall = partialBilling.spCall
   WHERE PmUserName= 'JOHN DOE'AND OpertionalStatus
    <> 'Billed' AND OpertionalStatus<> 'Finished' AND
     OpertionalStatus<> 'Passed To Billing' AND OpertionalStatus<> 'Scanning' 
     AND OpertionalStatus<> 'Ended' 
     AND OpertionalStatus<> 'Green Billing' 
     AND (GeneralStatus= 'Passed To Project Manager' 
     OR GeneralStatus= 'Astrategic Project') 
     GROUP BY Projects.SpCall,Projects.CustName,Projects.CustNumber
     ,Projects.ReceiveDate,Projects.StartDate,Projects.ProjectType
     ,Calculator.AN,Projects.Professional,Projects.PmUserName
     ,Projects.AcountManager,Projects.CrmCallNum,Projects.ProjectCategory
     ,Projects.CallNum,Projects.ContactName,Projects.ContactPhone
     ,Projects.ContactEmail,Projects.HiddenNote,Projects.RowColor
     , Projects.HeaderCellText,partialBilling.Ammount;

Answer 1

尝试使用 IFNULL()

SUM(IFNULL(Calculator.K,0) + ... + IFNULL(Calculator.AR,0)) AS sumofTotal

Answer 2

您可以使用 ifnull('column_name' , '') 等表达式代替 column_name。

Answer 3

而不是专有 IFNULL 更好地使用标准 SQL COALESCE:

SUM(COALESCE(Calculator.K,0) + COALESCE(Calculator.L,0), ...`

或者效率更高一点：

SUM(COALESCE(Calculator.K,0)) + SUM(COALESCE(Calculator.L,0)), ...`

SQL 查询：使用带左连接的聚合函数时不应为 NULL 的 NULL 值

SQL query: NULL values that should not be NULL when using aggregate function with left join

mysql

sql

aggregate-functions

left-join