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We can store the money values in MySQL in decimal(value1, value2). Here, value1 is the total range including value2. The value2 specifies the number of digits after the decimal point. To understand this concept, the steps are given below.First a table is created using the create command.mysql> CREATE table MoneyDemo -> ( -> Id int, -> Money decimal(10, 2) -> ); Query OK, 0 rows affected (0.46 sec)As can be seen from the above command, the decimal value has 10 digits only and also 2 digits only after the decimal point.After creating the table, some records are inserted with the ... Read More
The MySQL version before 5.0.3 was capable of storing 255 characters but from the version 5.0.3 , it is capable of storing 65, 535 characters.MySQL official documentation states −The effective maximum length of a VARCHAR in MySQL 5.0.3 and later is subject to the maximum row size (65, 535 bytes, which is shared among all columns) and the character set used. For example, utf8 characters can require up to three bytes per character, so a VARCHAR column that uses the utf8 character set can be declared to be a maximum of 21, 844 characters. Keep in mind that the limitation of ... Read More
The classList property returns the class name(s) of an element, as a DOMTokenList object. The classList property is read-only, however, you can modify it by using the add() and remove() methods.The classListproperty ensures that duplicate classes are not unnecessarily added to the element. In order to keep this functionality, if you dislike the longhand versions or jQuery version, I’d suggest adding addMany function and removeMany to DOMTokenListThese would then be useable like so −DOMTokenList.prototype.addMany = function(classes) { var arr = classes.split(' '); for (var j = 0, length = arr.length; j < length; j++) { this.add(array[j]); ... Read More
To find the port of the MySQL server, the command show can be used. Its syntax is as follows −show variables where variable_name=’port’;The above syntax is used to get the port number of the MySQL server using the following query −mysql> show variables where variable_name = 'port';After executing the above command, port of MySQL server is obtained as 3306. This can be seen in the following output −+---------------+-------+ | Variable_name | Value | +---------------+-------+ | port | 3306 | +---------------+-------+ 1 row in set (0.01 sec)Alternatively, the system variable @@port can also be used to find ... Read More
To find the records from one MySQL table which don’t exist in another table we can use the subquery for the table which does not have the records. This can be better understood using the given steps −First a table is created using the create command. The table name is ‘PresentHistory’ and it has two columns. This is given as follows −mysql> CREATE table PresentHistory -> ( -> HisID int, -> HisName varchar(100) -> ); Query OK, 0 rows affected (0.54 sec)After creating the table, some records are inserted that will be present in the second table as well. This ... Read More
When there is a requirement to pull down the screen to refresh the page to get latest updates, this can be done with the help of JavaScript, xhttprequests and then touch events.Pull refresh is a trigger to XHR in AJAX .It adds new data to the element we want.Pull refresh can be implemented with the help of hijacked JavaScript scrolling mechanism like iscroll. Twitter is using iscroll to pull refresh option.Another way is to create a refresh handler for overflow:scroll components.The interface provided can give an idea about the handler interface −var PullToRefresh= function(callback, wrapper, instructionsText) { //It ... Read More
The event source is just a web socket that -That cannot send data Uses text or event stream format It fires events that are server definedIt is useful in applications that only need server push.Web sockets are good for applications that need fast communications in both directions.Another major difference is the different security models they used.Server Send events are useful for −Live Feeds Live Scores Stock Market Update
In order to speed up creation and edition of HTML, splitting of HTML files are required into three separate HTML files −HeaderFooterContentThis is not possible in a static Html website; however, this is possible through PHP. Another way is to use JavaScript to load page pieces after the main page is already loaded.
In innoDB, NULL occupies less space as compared to empty string. Also, the NULL length is null while length of the empty string is 0.To understand this, a table is created with the help of create command which is given as follows −mysql> CREATE table DemoEmptyAndNULL -> ( -> Message varchar(100) -> ); Query OK, 0 rows affected (0.49 sec)After creating the table successfully, an empty record is inserted into the table with the help of insert command which is as follows −mysql> INSERT into DemoEmptyAndNULL values(' '); Query OK, 1 row affected (0.17 sec)After inserting the record, we can ... Read More
When we have a requirement in which we want to track the latest locations for a user only when they are in a certain area, then we write separate code for it. The code to determine when to prompt the user to share location in HTML is as follows -if (frstTime) { //First time navigator.getCurrentPosition(function (coordinates) { if (coordsAreInTheBox) { storeCoordsForUser(); navigator.watchPosition(); } }); ... Read More