SQL Date () function

Source: Internet
Author: User
Tags getdate time interval

SQL Server Date function

The following table lists the most important built-in date functions in SQL Server:

function Description
GETDATE () Returns the current date and time
DATEPART () Returns a separate part of the date/time
DATEADD () Add or subtract a specified time interval in a date
DATEDIFF () Returns a time between two dates
CONVERT () Display Date/time in a different format

The (1), GETDATE () function returns the current date and time from SQL Server.

GrammarGETDATE () Example

Here is the SELECT statement:

SELECT GETDATE () as Currentdatetime

The results are as follows:

Currentdatetime
2008-11-11 12:45:34.243

(2),

The DATEPART () function is used to return a separate part of a date/time, such as year, month, day, hour, minute, and so on.

GrammarDATEPART (Datepart,date)

The date parameter is a valid day expression. The datepart parameter can be the following value:

DatePart Abbreviations
Years YY, yyyy
Quarter QQ, Q
Month MM, M
The day of the year Dy, y
Day DD, D
Week WK, WW
Week DW, W
Hours hh
Minutes MI, n
Seconds SS, S
Milliseconds Ms
Subtle MCs
Na-Sec Ns
Example

Suppose we have the following "Orders" table:

OrderId ProductName OrderDate
1 Jarlsberg Cheese 2008-11-11 13:23:44.657

Here is the SELECT statement:

SELECT DATEPART (yyyy,orderdate) as OrderYear, DATEPART (mm,orderdate) as OrderMonth, DATEPART (dd,orderdate) as Orderday, From Orders WHERE orderid=1

The results are as follows:

OrderYear OrderMonth Orderday
2008 11 11

(3),

The DATEADD () function adds or subtracts a specified time interval from a date.

GrammarDATEADD (Datepart,number,date)

The date parameter is a valid day expression. The number is the number of intervals you want to add, and for the future time, this is positive, and for the past time, this number is negative.

The datepart parameter can be the following value:

DatePart Abbreviations
Years YY, yyyy
Quarter QQ, Q
Month MM, M
The day of the year Dy, y
Day DD, D
Week WK, WW
Week DW, W
Hours hh
Minutes MI, n
Seconds SS, S
Milliseconds Ms
Subtle MCs
Na-Sec Ns
Example

Suppose we have the following "Orders" table:

OrderId ProductName OrderDate
1 Jarlsberg Cheese 2008-11-11 13:23:44.657

Now we want to add 45 days to "OrderDate" so we can find the payment date.

We use the following SELECT statement:

SELECT Orderid,dateadd (day,45,orderdate) as orderpaydate from Orders

Results:

OrderId orderpaydate
1 2008-12-26 13:23:44.657

(4),

The DATEDIFF () function returns the number of days between two dates.

GrammarDATEDIFF (Datepart,startdate,enddate)

The StartDate and EndDate parameters are valid date expressions. The datepart parameter can be the following value:

DatePart Abbreviations
Years YY, yyyy
Quarter QQ, Q
Month MM, M
The day of the year Dy, y
Day DD, D
Week WK, WW
Week DW, W
Hours hh
Minutes MI, n
Seconds SS, S
Milliseconds Ms
Subtle MCs
Na-Sec Ns
Example

Now we want to get a number of days between two dates.

We use the following SELECT statement:

SELECT DATEDIFF (Day, ' 2008-06-05 ', ' 2008-08-05 ') as Diffdate

Results:

Diffdate
61
Example

Now we want to get two days between dates (note that the second date is earlier than the first date and the result will be a negative number).

We use the following SELECT statement:

SELECT DATEDIFF (Day, ' 2008-08-05 ', ' 2008-06-05 ') as Diffdate

Results:

Diffdate
-61

(5),

The CONVERT () function is a general function that converts a date to a new data type.

The CONVERT () function can display date/time data in different formats.

Grammar convert ( data_type (length), expression, style)
value Description
Data_type (length) Specifies the target data type (with an optional length).
Expression Specifies the value that needs to be converted.
Style Specifies the date/time of the output format.

The following table shows the style values that are converted to character data by datetime or smalldatetime:

value (Century yy) value (century yyyy) Input/Output Standard
- 0 or 100 Mon dd yyyy hh:miam (or PM) Default
1 101 Mm/dd/yy USA
2 102 Yy.mm.dd Ansi
3 103 Dd/mm/yy British/french
4 104 Dd.mm.yy German
5 105 Dd-mm-yy Italian
6 106 DD Mon yy
7 107 Mon DD, yy
8 108 Hh:mm:ss
- 9 or 109 Mon dd yyyy hh:mi:ss:mmmAM (or PM) Default+millisec
10 110 Mm-dd-yy USA
11 111 Yy/mm/dd Japan
12 112 Yymmdd Iso
- 113 or DD Mon yyyy hh:mi:ss:mmm (24h)
14 114 Hh:mi:ss:mmm (24h)
- 120 or Yyyy-mm-dd Hh:mi:ss (24h)
- or 121 Yyyy-mm-dd hh:mi:ss.mmm (24h)
- 126 Yyyy-mm-ddthh:mi:ss.mmm (no spaces) ISO8601
- 130 DD Mon yyyy hh:mi:ss:mmmAM Hijiri
- 131 Dd/mm/yy Hh:mi:ss:mmmAM Hijiri
Example

The following script uses the CONVERT () function to display different formats. We will use the GETDATE () function to get the current date/time:

CONVERT (varchar), GETDATE ()) CONVERT (varchar (), GETDATE (), () convert (varchar), GETDATE (), () Convert ( varchar (one), GETDATE (), 6) CONVERT (varchar (one), GETDATE (), 106) CONVERT (varchar), GETDATE (), 113)

The results are as follows:

Nov 11:45 PM 11-04-11 11-04-2011, Geneva 2011 11:45:34:243

SQL Date () function

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