修改SQL語句以從表中追加一列

Question

我有兩個表：TrainingMatrix和Data。對於TrainingMatrix我有這樣的SQL語句：

SELECT DISTINCT ON (payroll, "TrainingName", "Institute") * 
      FROM "TrainingMatrix" 
      ORDER BY payroll, "TrainingName", "Institute" ,"TrainingDate" DESC NULLS LAST; 

每個工資號是關係到一個唯一的僱員姓名。所以，在Data表中我有兩列：payroll和"EmployeeName"。我如何修改前面的陳述，以便我可以顯示/項目"EmployeeName"以及結果。

我使用PostgreSQL 9.2和pgAdmin III。

Answer 1

你可以加入與Data表查詢：

SELECT DISTINCT ON ("TrainingMatrix".payroll, "TrainingName", "Institute") "Data".EmployeeName, "TrainingMatrix".* 
FROM "TrainingMatrix" 
JOIN "Data" ON "TrainingMatrix".payroll = "Data".payroll 
ORDER BY payroll, "TrainingName", "Institute" ,"TrainingDate" DESC NULLS LAST;