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SQL Server uses '1900-01-01' as a "zero-point" in DATEDIFF(dd, 0, some_date): select DATEDIFF(dd, 0, '1900-01-01') --> 0 select DATEDIFF(dd, 0, GETDATE()) --> 44066 days since the "zero-d...
Answer
#3: Post edited
by
Alexei
·
2020-10-20T15:39:51Z (about 4 years ago)
added explicit SO reference name
- SQL Server uses '1900-01-01' as a "zero-point" in `DATEDIFF(dd, 0, some_date)`:
- select DATEDIFF(dd, 0, '1900-01-01') --> 0
- select DATEDIFF(dd, 0, GETDATE()) --> 44066 days since the "zero-day"
- The whole expression is used to strip time from the `DATETIME` and still have it as a DATETIME (as opposed to DATE). An alternative would be to `CAST` it to DATE, but it will change the type:
- select CAST(GETDATE() AS DATE) --> 2020-08-25 (no time)
- What is more interesting is that the minimum DATETIME is not '1900-01-01', but 1753-01-01 which of course corresponds to a negative integer value:
- select cast(-53690 as datetime)
- Relevant resources:
[SQL Server function to return minimum date ](https://stackoverflow.com/questions/3825893/sql-server-function-to-return-minimum-date-january-1-1753)[Best approach to remove time part of datetime in SQL Server](https://stackoverflow.com/questions/1177449/best-approach-to-remove-time-part-of-datetime-in-sql-server)
- SQL Server uses '1900-01-01' as a "zero-point" in `DATEDIFF(dd, 0, some_date)`:
- select DATEDIFF(dd, 0, '1900-01-01') --> 0
- select DATEDIFF(dd, 0, GETDATE()) --> 44066 days since the "zero-day"
- The whole expression is used to strip time from the `DATETIME` and still have it as a DATETIME (as opposed to DATE). An alternative would be to `CAST` it to DATE, but it will change the type:
- select CAST(GETDATE() AS DATE) --> 2020-08-25 (no time)
- What is more interesting is that the minimum DATETIME is not '1900-01-01', but 1753-01-01 which of course corresponds to a negative integer value:
- select cast(-53690 as datetime)
- Relevant resources:
- [SQL Server function to return minimum date ](https://stackoverflow.com/questions/3825893/sql-server-function-to-return-minimum-date-january-1-1753) from Stack Overflow.
- [Best approach to remove time part of datetime in SQL Server](https://stackoverflow.com/questions/1177449/best-approach-to-remove-time-part-of-datetime-in-sql-server) from Stack Overflow.
#2: Post edited
by
Alexei
·
2020-08-25T05:48:52Z (over 4 years ago)
clarified that number is expressed in days
- SQL Server uses '1900-01-01' as a "zero-point" in `DATEDIFF(dd, 0, some_date)`:
- select DATEDIFF(dd, 0, '1900-01-01') --> 0
select DATEDIFF(dd, 0, GETDATE()) --> 44066- The whole expression is used to strip time from the `DATETIME` and still have it as a DATETIME (as opposed to DATE). An alternative would be to `CAST` it to DATE, but it will change the type:
- select CAST(GETDATE() AS DATE) --> 2020-08-25 (no time)
- What is more interesting is that the minimum DATETIME is not '1900-01-01', but 1753-01-01 which of course corresponds to a negative integer value:
- select cast(-53690 as datetime)
- Relevant resources:
- [SQL Server function to return minimum date ](https://stackoverflow.com/questions/3825893/sql-server-function-to-return-minimum-date-january-1-1753)
- [Best approach to remove time part of datetime in SQL Server](https://stackoverflow.com/questions/1177449/best-approach-to-remove-time-part-of-datetime-in-sql-server)
- SQL Server uses '1900-01-01' as a "zero-point" in `DATEDIFF(dd, 0, some_date)`:
- select DATEDIFF(dd, 0, '1900-01-01') --> 0
- select DATEDIFF(dd, 0, GETDATE()) --> 44066 days since the "zero-day"
- The whole expression is used to strip time from the `DATETIME` and still have it as a DATETIME (as opposed to DATE). An alternative would be to `CAST` it to DATE, but it will change the type:
- select CAST(GETDATE() AS DATE) --> 2020-08-25 (no time)
- What is more interesting is that the minimum DATETIME is not '1900-01-01', but 1753-01-01 which of course corresponds to a negative integer value:
- select cast(-53690 as datetime)
- Relevant resources:
- [SQL Server function to return minimum date ](https://stackoverflow.com/questions/3825893/sql-server-function-to-return-minimum-date-january-1-1753)
- [Best approach to remove time part of datetime in SQL Server](https://stackoverflow.com/questions/1177449/best-approach-to-remove-time-part-of-datetime-in-sql-server)
#1: Initial revision
by
Alexei
·
2020-08-25T05:17:25Z (over 4 years ago)
SQL Server uses '1900-01-01' as a "zero-point" in `DATEDIFF(dd, 0, some_date)`:
select DATEDIFF(dd, 0, '1900-01-01') --> 0
select DATEDIFF(dd, 0, GETDATE()) --> 44066
The whole expression is used to strip time from the `DATETIME` and still have it as a DATETIME (as opposed to DATE). An alternative would be to `CAST` it to DATE, but it will change the type:
select CAST(GETDATE() AS DATE) --> 2020-08-25 (no time)
What is more interesting is that the minimum DATETIME is not '1900-01-01', but 1753-01-01 which of course corresponds to a negative integer value:
select cast(-53690 as datetime)
Relevant resources:
[SQL Server function to return minimum date ](https://stackoverflow.com/questions/3825893/sql-server-function-to-return-minimum-date-january-1-1753)
[Best approach to remove time part of datetime in SQL Server](https://stackoverflow.com/questions/1177449/best-approach-to-remove-time-part-of-datetime-in-sql-server)