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Articles on Trending Technologies
Technical articles with clear explanations and examples
What happens when MySQL encounters an out-of-range date?
The response of MySQL on encountering out-of-range or invalid date will depend upon SQL MODE. If we have enabled ALLOW_INVALID_DATES mode then MySQL will convert the out of range values into all zeros (i.e. ‘0000:00:00 00:00:00’) and also stores the same in the table without producing any error or warning.For example, we can change SQL MODE as follows and then insert the out-of-range −mysql> set sql_mode = 'ALLOW_INVALID_DATES'; Query OK, 0 rows affected (0.00 sec) mysql> Insert into order1234(productname, quantity, orderdate) values('A', 500, '999-05-100'); Query OK, 1 row affected, 1 warning (0.13 sec) mysql> Select * from order1234; ...
Read MoreHow can we allow MySQL to store invalid dates?
After enabling the SQL MODE to ALLOW_INVALID_DATES, MySQL will also be able to store invalid dates in the table. The example is given below to understand it −mysql> Insert into order1234(ProductName, Quantity, Orderdate) values('B',500,'2015-11-31'); Query OK, 1 row affected (0.06 sec) mysql> Select * from order1234; +-------------+----------+--------------+ | ProductName | Quantity | OrderDate | +-------------+----------+--------------+ | A | 500 | 0000-00-00 | | B | 500 | 2015-11-31 | +-------------+----------+--------------+ 2 rows in set (0.00 sec)We can see MySQL also inserts the invalid date in a table.
Read MoreHow to Create 301 Redirection on Nginx and Apache
In this article, we will learn how to redirect the URLs or Domain to another address. This can be done by using the HTTP Redirection. The URL redirection is a popular technique to point one domain address to another domain address which we can achieve on Apache and Nginx both.Redirecting to an another DomainWe might face a situation in which, we have an established web-site and we need to change the domain for the site. Here, we cannot do this by deleting the older domain since this may cause breakage and disappearance of contents on the old domain is possible ...
Read MoreIn MySQL, how we can compute date by providing the year, week number and day of the week?nday of the week?
We can compute the date as follows −mysql> SET @year=2017, @week=15, @day=4; Query OK, 0 rows affected (0.00 sec)The above query will pass the value’2017’ ,’15’, ‘4’ in ‘year’, ’week’ and ‘day’ variables respectively. Then after applying the formula in the query below, we can get the date.mysql> SELECT Str_To_Date( Concat(@year,'-',@week,'-',If(@day=7,0,@day) ), '%Y-%U-%w' ) AS Date; +--------------+ | Date | +--------------+ | 2017-04-13 | +--------------+ 1 row in set (0.00 sec)
Read MoreHow to download APK files from Google Play Store on Linux
Do you know how to download APK (Android packaging kit) files from Google Play store on Linux? One of the easiest way is to install APK on Android mobile for downloading APK files from Google Play Store to Hard Disk and install them on the Android device manually.There are several ways to download APK file(s) on Linux. One of the most used ways is via an open-source Linux software called GooglePlayDownloader. It works on python based GUI. It enables you to search and download APK files from Google play store. This article gives information about, how to install GooglePlayDownloader and ...
Read MoreWhat is the way to find business days between two specified dates in MySQL?
With the help of DATEDIFF(expr1, expr2) we can find the business days between two specified dates.For example, if we want to find business days between ‘2017-05-27’ and ‘2017-05-23’ then following would be MySQL query −mysql> Select DATEDIFF('2017-05-27','2017-05-23') AS 'Total Business Days'; +----------------------+ | Total Business Days | +----------------------+ | 4 | +----------------------+ 1 row in set (0.00 sec)
Read MoreIn MySQL, when VARCHAR data type will use 1-byte and when 2-bytes prefix length along with data?length along with data?
As we know that in MySQL, VARCHAR values are stored as a 1-byte or 2-byte length prefix plus data. This length prefix points out the number of bytes in the value of data. The data value itself will decide that when VARCHAR data type will use 1-byte and when 2-byte prefix length.A column uses 1-byte length if values require no more than 255 bytes.A column uses 2-byte length if values may require more than 255 bytes.
Read MoreWhy we cannot use MySQL DATE data type along with time value?
The default format for MySQL DATE data type is “YYYY-MM-DD” and in this format, there is no possibility to store the time value. Hence, we can say that we cannot use DATE data type along with time value.As we can see in the following example MySQL returns only date value even on using time along with the date.mysql> select DATE("2017-09-25 09:34:21"); +-----------------------------------+ | DATE("2017-09-25 09:34:21") | +-----------------------------------+ | 2017-09-25 | +-----------------------------------+ 1 row in set (0.04 sec)However, in DATETIME and TIMESTAMP date data types we can use the time to date.
Read MoreHow to search a record by date in MySQL table?
Suppose we have a table ‘Order123’ having ProductName, Quantity and OrderDate columns as follows −mysql> Select * from Order123; +-------------+----------+------------+ | ProductName | Quantity | OrderDate | +-------------+----------+------------+ | A | 100 | 2017-05-25 | | B | 105 | 2017-05-25 | | C | 55 | 2017-05-25 | | D | 250 | 2017-05-26 | | E | 500 | 2017-05-26 | | ...
Read MoreWhat happens if I will delete a row from MySQL parent table?
While deleting the row from the parent table, if the data of that row is used in the child table then MySQL will throw an error because of the failure of FOREIGN KEY constraint. It can be understood with the example of two tables named ‘customer’ and ‘orders’. Here, ‘customer’ is the parent table and ‘orders’ is the child table. We cannot delete a row, that is used in child table ‘orders’, from the ‘customer’ table. It can be demonstrated by deleting the values from the parent table as follows −mysql> Select * from Customer; +----+--------+ | id | name ...
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