在postgres中将日期格式从varchar更改为yyyy-mm-dd

Question

SELECT
  to_char("date", 'YYYY/MM/DD') 
  "public".teacher_details.teacher_id,
  "public".teacher_details.first_name,
  "public"."TblFacultyMaster"."MastCode",
  "public"."TblFacultyMaster"."MastName",
  "public"."TblFacultyMaster"."DOB",
  "public".teacher_details.dob
FROM
  "public".teacher_details
INNER JOIN "public"."TblFacultyMaster" ON "public"."TblFacultyMaster".teacher_id = "public".teacher_details.teacher_id

我正在尝试将日期格式从dd / mm / yyyy转换为yyyy-mm-dd，类型为varchar，因为我的TblFacultyMaster表格格式为yyyy-mm-dd，而dd / mm / yyyy格式为teachers_deatil表 我想匹配常见的DOB，但两个表格中的格式不同

请帮助

提前致谢

Answer 1

datecolumn无法将字符串转换为字符串，尝试使用日期对varchar SELECT to_char("date"::date, 'YYYY/MM/DD') as date, "public".teacher_details.teacher_id, "public".teacher_details.first_name, "public"."TblFacultyMaster"."MastCode", "public"."TblFacultyMaster"."MastName", "public"."TblFacultyMaster"."DOB", "public".teacher_details.dob FROM "public".teacher_details INNER JOIN "public"."TblFacultyMaster" ON "public"."TblFacultyMaster".teacher_id = "public".teacher_details.teacher_id 进行类型转换，我想“日期”是您的那一列，请尝试  如下所示：

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Answer 2

SELECT
  to_char(to_date(dob, 'dd/mm/yyyy'),'YYYY/MM/DD'),  
  "public".teacher_details.teacher_id,
  "public".teacher_details.first_name,
  "public"."TblFacultyMaster"."MastCode",
  "public"."TblFacultyMaster"."MastName",
  "public"."TblFacultyMaster"."DOB",
  "public".teacher_details.dob
FROM
  "public".teacher_details
INNER JOIN "public"."TblFacultyMaster" ON "public"."TblFacultyMaster".teacher_id = "public".teacher_details.teacher_id

未经测试

Answer 3

使用to_date（）函数时，PostgreSQL会自动将其带到yyyy-MM-dd。见下文：

select to_date(dob, 'dd/mm/yyyy') as myDate;

这将产生以下结果：

我希望有所帮助。欢呼声。

编辑：

好的，我明白你要做的是什么，也许这会解决问题：

SELECT
  to_date("public".teacher_details.dob, 'dd/MM/yyyy'),
  "public".teacher_details.teacher_id,
  "public".teacher_details.first_name,
  "public"."TblFacultyMaster"."MastCode",
  "public"."TblFacultyMaster"."MastName",
  "public"."TblFacultyMaster"."DOB",
  "public".teacher_details.dob
FROM
  "public".teacher_details
INNER JOIN "public"."TblFacultyMaster" ON "public"."TblFacultyMaster".teacher_id = "public".teacher_details.teacher_id
WHERE to_date("public".teacher_details.dob, 'dd/MM/yyyy') = "public"."TblFacultyMaster".dob