仅当记录匹配时更新一个 table 中的记录

Question

我希望用 Patientdemographics2 中名为 custom 的列更新 Patientdemographics 中名为 custom 的列，但前提是 FirstName LastName 和 DateofBirth 列在两个表中都匹配。

Update PatientDemographics
Set PatientDemographics.custom = PatientDemographics2.custom       
FROM            PatientDemographics INNER JOIN
                         PatientDemographics2 ON
                         Patientdemographics.FirstName = Patientdemographics2.FirstName and
                         Patientdemographics.LastName = Patientdemographics2.LastName  and 
                         Patientdemographics.DateofBirth = Patientdemographics.DateofBirth
                         where Patientdemographics.FirstName = Patientdemographics2.FirstName and
                         Patientdemographics.LastName = Patientdemographics2.LastName  and 
                         Patientdemographics.DateofBirth = Patientdemographics.DateofBirth

Answer 1

您在 ON 子句的最后一个条件中有错字：

Patientdemographics.DateofBirth = Patientdemographics.DateofBirth

应该是：

Patientdemographics.DateofBirth = Patientdemographics2.DateofBirth

还有一个 useless WHERE 子句，因为它的所有条件都已经应用在 ON 子句中。
也使用别名使代码更简单和更易读：

Update p
Set p.custom = p2.custom       
FROM PatientDemographics AS p INNER JOIN PatientDemographics2 AS p2 
ON
  p.FirstName = p2.FirstName and
  p.LastName = p2.LastName  and 
  p.DateofBirth = p2.DateofBirth

仅当记录匹配时更新一个 table 中的记录

Update records in one table from another only if records match

sql

sql-server

sql-server-2014