The date calculation function for PostgreSQL uses

One: Connectors in individual data

Connector for SQL Server: + (plus)

SQLite's connector:. (dot)

Connector for PostgreSQL: | | Or

Two:

Today, when PostgreSQL calculates the date, I turn over some information, rarely, record it!

The functions and variables used in these

To_char (), Date (), now (), current_date

Calculates the difference of two dates

Current_date is today's date, as: 2015-06-03

Date (' 2015-06-05 ')-current_date=2

Select To_char (current_date, ' yyyy ') | | ' -' | | To_char (Birthday, ' mm-dd '), Date (To_char (current_date, ' yyyy ') | | ' -' | | To_char (Birthday, ' mm-dd '))-current_date

From TableName where delflag=0 and status=0

and Date (To_char (current_date, ' yyyy ') | | ' -' | | To_char (Birthday, ' mm-dd '))-current_date>=0

and Date (To_char (current_date, ' yyyy ') | | ' -' | | To_char (Birthday, ' mm-dd '))-current_date<=7order by birthday desc

Three:

select  Now () +  interval  '  1 days  "   

select  Now () +  interval  '  1 month  "   

Select + ' 1 Years '

Four:

when you perform date calculations in SQL Server, use the function

CONVERT (), DATEPART (), GetDate ()

Select CONVERT (varchar), CONVERT (varchar (4), DATEPART (Year,getdate ())) + '-' + CONVERT (varchar (2), DATEPART (month, Birthday) + '-' +convert (varchar (2), DATEPART (Day,birthday)), DateDiff (day,convert (varchar), GETDATE (), 120) , convert (varchar), CONVERT (varchar (4), DATEPART (Year,getdate ())) + '-' + CONVERT (varchar (2), DATEPART (month, Birthday) + '-' +convert (varchar (2), DATEPART (Day,birthday)), 120))

From TableName where delflag=0 and status=0

Birthday desc

The date calculation function for PostgreSQL uses