sql - 修改 SQL 语句以追加表中的列

Question

我有两个表:TrainingMatrix 和 Data。对于 TrainingMatrix 我有这个 SQL 语句:

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

每个工资单号都与唯一的员工姓名相关。因此，在 Data 表中我有两列:payroll 和 "EmployeeName"。我如何修改前面的语句，以便我也可以用结果显示/投影 "EmployeeName"。

我使用 PostgreSQL 9.2 和 pgAdmin III。

Answer 1

您可以将查询与 Data 表结合起来:

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;