N.categoryid C.categoryid,c.[name]First query statement: Select C.categoryid,c.[name] from Category C left join News N in C.categoryid=n.categoryid where N.categoryid is NullSecond query statement: Select Categoryid,[name] from category where NOT exists(SELECT * FROM News where Category.categoryid=news.categoryid)* The first performance is undoubtedly the best when the CategoryID is not repeated in the news table, whereas the second performance is good.11.SQL Statement conversion Format functio
Timestamp: is a time representation, defined as the total number of seconds from GMT January 01, 1970 00:00 00 seconds to the present. Unix timestamps are used not only in UNIX systems, Unix-like systems, but also in many other operating systems.1. Convert Timestamps to date formats1 //a simple line of code2 varDate =NewDate (timestamp);//gets a Time object3 4 /
.exists Find out that the CategoryID in the category table are not equal to N.categoryid C.categoryid,c.[name] First query statement: Select C.categoryid,c.[name] from Category C left join News N in C.categoryid=n.categoryid where N.categoryid is Null Second query statement: Select Categoryid,[name] from category where NOT exists ( SELECT * FROM News where Category.categoryid=news.categoryid ) * The first performance is undoubtedly the best when the CategoryID is not repeated in the news table,
necessary to convert each other, the following gives the conversion of several different ways. One, complete in MySQL This way in the MySQL query statement conversion, the advantage is not to occupy PHP parser parsing time, fast, the disadvantage is only used in database query, there are limitations. 1. UNIX timestamp converted to date function: From_unixtime () General form: Select From_unixtime (11562198
remove the last three bits, otherwise return null
Unix_timestamp (date)
Returns a UNIX timestamp (the number of seconds since ' 1970-01-01 00:00:00 ' GMT) if no parameter calls are invoked. If Unix_timestamp () is invoked with a date parameter, it returns the number of seconds that start from ' 1970-01-01 00:00:00 '
In mysql, we often use the CONVERT () function to format the time and date of the CONVERT type. below I will introduce you to the usage of the CONVERT () function in detail, for your reference.
In mysql, we often use the CONVERT () function to format the time and
SQL CONVERT () string int-type Date character type
Convert to date notation
Convert (data_type (length), Data_to_be_converted,style)
Instance
Select CONVERT (varchar), GETDATE (), () now
This article describes how to convert a js timestamp to a date format. If you are interested, refer to the Unix timestamp: Unix timestamp ), or Unix time or POSIX time is a time representation, it is defined as the total number of seconds from GMT, January 1, January 01, 1970 to the present. Unix timestamps are not only used in Unix and Unix-like systems, but als
Tags: ar sp strong data on the art code BSDatabase (string function, Date function, data type conversion Cast,convert)Use studentGoCREATE TABLE Yuangong(code int,Name varchar (20),Sex varchar (20),Age int,Bumen varchar (20),)INSERT into Yuangong values (1, ' Week number ', ' Male ', 27, ' sales Department ')INSERT into Yuangong values (1, ' King of the Week ', '
In this section you will learn to convert the date into a long format.Java. utilPackage provides the functionality to convert a date type into a long type.
Description of program:
The following program helps you in converting a date into a long type. First of all you need a
Get current time:var mydate = new Date ();//Current timevar year = Mydate.getfullyear ();//Current yearsvar month = Mydate.getmonth () + 1;//Current Monthvar day = Mydate.getdate ();//Current dateMydate.getyear (); Get Current year (2-bit)Mydate.getfullyear (); Get the full year (4-bit, 1970-????)Mydate.getmonth (); Get the current month (0-11, 0 for January)Mydate.getdate (); Get current day (1-31)Mydate.getday (); Get Current week x (0-6, 0 for Sund
The DB2 unique sequential number generation recently developed system requires that many unique document numbers be generated. The rule prefix of the document number is _ yyyyMMdd + sequential number, such as P_201210160001 and P_201210160002. Because multiple document numbers are generated. Therefore, a seed table nam
But what if you want to show different areas of time —--for example, if your part is in another country, what do you do if you want to see "home" time instead of local time?
To do this, a variety of time calculations are required to convert local time to destination time. This article explains how to do these calculations.
First step:
The first step in the business is to get local time. In JavaScript, this can undoubtedly be done easily by initializin
Year Month Day hour minute second:". date ("Y-m-d H: I: s", time (). "\ n ";
// Display in minutes
Echo "time () shows only the year, month, and day:". date ("Y-m-d", time (). "\ n"; // only the year, month, and day are displayed.
Echo "timestamp format:". date ("Y-m-d H: I: s", 1297845628). "\ n"; // use the timestamp directly.
//
Label:
The principle is to take the middle of the number of milliseconds, and then converted to JS date type Function Changedateformat (val) { if (val! = null) { var date = new Date (parseint ("Val.replace" ("/date", "" "). Replace (")/"," "), 10));
When an enterprise lends to banks and individuals, to calculate the number of days between the loan date and the repayment date in Excel, Excel2007 can use the DateValue function to calculate the number of days between the loan date and the repayment
days and months, these two issues are resolved.
A number of time functions have been listed in the previous article, and now the cast and convert used in this article are described in detail:
Let's take a look at their grammar:
CAST (expression as data_type [(length)])
CONVERT (data_type [(length)], expression [, style])
which
Expression: Any valid expressi
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