Postgresql 如何在Postgres Sql中两次选择不同格式的同一列？

我想要实际的列值和截断的列值，如下所示。谁都可以帮忙

Select "sub1"."TimestampField","month_trunc1","month_trunc2" 
from (
   Select  "Id", date_trunc('month', "TimestampField") as "month_trunc1", "TimestampField" 
   from "Table"
) as "sub1", (
  Select  "Id", date_trunc('month', "TimestampField") as "month_trunc2", "TimestampField" 
  from "Table"
) as "sub2" 
WHERE "month_trunc2" = ("month_trunc1"+interval '1 month');

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通过在同一个表上使用JOIN，可以简化示例：

 SELSECT 
   "sub1"."mainfield",
   "sub1"."TimestampField" as month1, 
   "sub2"."TimestampField" as month2, 
   date_trunc('month', "sub1"."TimestampField") as "month_trunc1", 
   date_trunc('month', "sub2"."TimestampField") as "month_trunc2"
 FROM "Table" "sub1" 
 JOIN "Table" "sub2"
       ON "month_trunc2" = ("month_trunc1"+interval '1 month');

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请回答您的问题，并根据这些数据添加一些内容和预期输出。请（您的问题-请勿在注释中发布代码或其他信息）请注意，postgres不能在第条中使用别名，因此您必须将“month__-thrunc1/2”替换为完整的语句日期（“month”，“sub1/2”，“TimestampField”），我希望实际的TimestampField值和截断的TimestampField值date_-trunc（“month”，“TimestampField”）“月份\u trunc1”，“时间戳字段”