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--(Take the system time as an example, the actual situation can be replaced)1 Read system time –sysdateSelect sysdate from dual;2 Read time information (year, month, day, hour, minute, second)Select To_char (sysdate, ' Yyyy-mm-dd hh24:mi:ss ') as nowtime from dual; Date converted to stringSelect To_char (sysdate, ' yyyy ') as nowyear from dual; Get the year of the timeSelect To_char (sysdate, ' mm ') as now

data through graphical user interfaces, and a unique key is generated by the computer as the primary key of this record. How can we find redundant data? Let's create a table named "Customer" and add redundant data to it. let's see Table 1. as you can see, we have not made any restrictions on this table to prevent redundant data, the following code creates a unique constraint to prevent redundant data generation.SQLListing 1. create a Customer tableWe intentionally added redundant data to this t

April 24, 2008System.DateTime.Now.ToString ("D");2008-4-24System.DateTime.Now.ToString ("D");April 24, 2008 16:30:15System.DateTime.Now.ToString ("F");April 24, 2008 16:30System.DateTime.Now.ToString ("F");2008-4-24 16:30:15System.DateTime.Now.ToString ("G");2008-4-24 16:30System.DateTime.Now.ToString ("G");16:30:15System.DateTime.Now.ToString ("T");16:30 System.DateTime.Now.ToString ("T");April 24, 2008 8:30:15System.DateTime.Now.ToString ("U");2008-04-24 16:30:15zSystem.DateTime.Now.ToString (

Tags: style blog color using AR sp div on COracle Two time subtraction default is the number of days Oracle two time subtraction default is the number of days* -The number of hours for the difference Oracle two time subtraction The default is the number of days* -* -number of minutes for difference Oracle two time subtraction The default is the number of days* -* -* -the number of seconds to vary--Months_between (date2,date1)Give the Date2-date1 month of SQL> SelectMonths_between ('1 September-D

Oracle Two time subtraction default is the number of daysOracle two time subtraction The default is the number of days *24 is the difference between the hoursOracle two time subtraction The default is the number of minutes *24*60 is the difference betweenOracle two time subtraction default is the number of days *24*60*60 is the difference in seconds--months_between (DATE2,DATE1)Give the month of date2-date1sql> Select months_between ('1 September-December -1999','1 September-March-1999 ') mon_

data file can span multiple physical disks. Here is the code to create the table and partition, as follows:CREATE TABLE Emp_range(EMPNO number NOT NULL primary key,DEPTNO number is not NULL,First_Name VARCHAR2 (+) NOT NULL,Last_Name VARCHAR2 (+) NOT NULL,Status char (1),Hire_date date NOT NULL)Partition by range (hire_date)(Partition Hire_part1 values less than (to_date (' 2017-04-01 ', ' yyyy-mm-dd ') tablespace emp_space01,Partition Hire_part2 valu

sin (20), sinh (20) from dual; sin (20) sinh (20 )------------------. 91294525 24258259832. SQRT returns the number N root SQL> select SQRT (64), SQRT (10) from dual; SQRT (64) SQRT (10) --------- 8 3.162277733.tan returns the tangent of a number. SQL> select Tan (20), Tan (10) from dual; Tan (20) Tan (10) --------- ------- 2.2371609. 6483608334. tanh returns the hyperbolic tangent of number n SQL> select Tanh (20), Tan (20) from dual; Tanh (20) Tan (20) --------- 1 2.2371609 35. trunc intercep

meet the time range limit Query the Oracle Date Format---------------------------------- Select * From nls_database_parameters; The following table shows the date format in the table nls_date_format.Parameter Value----------------------------------------------------------------------Nls_language AmericanNls_territory AmericaNls_currency $Nls_iso_currency AmericaNls_numeric_characters .,Nls_characterset zhs16gbkNls_calendar GregorianNls_date_format DD-MON-RRNls_date_language AmericanNls_s

The first day of a month SELECT to_date(to_char(SYSDATE,'yyyy-mm')||'-01','yyyy-mm-dd')FROM dual Sysdate is the current system time of the database server.To_char is a function that converts a date type into a date type.To_date is a function that converts the string type to the date type. Generally, the format is yyyy-mm-dd hh24: mi: ss. If no time is specifi

Reprinted from: http://blog.csdn.net/redarmy_chen/article/details/7351410 Oracle Two-time subtraction default is days Oracle Two-time subtraction default is the number of days *24 to the difference in hours Oracle Two-time subtraction the default is the number of days *24*60 to the difference in minutes Oracle Two-time subtraction the default is the number of days *24*60*60 to the difference in seconds --months_between (DATE2,DATE1)Give out the month of date2-date1Sql> Select Months_between ('

April 24, 2008System.DateTime.Now.ToString ("D");2008-4-24System.DateTime.Now.ToString ("D");April 24, 2008 16:30:15System.DateTime.Now.ToString ("F");April 24, 2008 16:30System.DateTime.Now.ToString ("F");2008-4-24 16:30:15System.DateTime.Now.ToString ("G");2008-4-24 16:30System.DateTime.Now.ToString ("G");16:30:15System.DateTime.Now.ToString ("T");16:30System.DateTime.Now.ToString ("T");April 24, 2008 8:30:15System.DateTime.Now.ToString ("U");2008-04-24 16:30:15zSystem.DateTime.Now.ToString ("

24System.DateTime.Now.ToString ("M");System.DateTime.Now.ToString ("M");Tue, APR 2016 16:30:15 GMTSystem.DateTime.Now.ToString ("R");System.DateTime.Now.ToString ("R");June 2016System.DateTime.Now.ToString ("Y");System.DateTime.Now.ToString ("Y");2016-04-24t15:52:19.1562500+08:00System.DateTime.Now.ToString ("O");System.DateTime.Now.ToString ("O");2016-04-24t16:30:15System.DateTime.Now.ToString ("s");2016-04-24 15:52:19System.DateTime.Now.ToString ("Yyyy