karthikeya Boyini

karthikeya Boyini

1,421 Articles Published

Articles by karthikeya Boyini

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What is a hit count for a Webpage?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 904 Views

A hit counter tells you about the number of visits on a particular page of your web site. Usually, you attach a hit counter with your index.jsp page assuming people first land on your home page.To implement a hit counter you can make use of the Application Implicit object and associated methods getAttribute() and setAttribute().This object is a representation of the JSP page through its entire lifecycle. This object is created when the JSP page is initialized and will be removed when the JSP page is removed by the jspDestroy() method.Following is the syntax to set a variable at the ...

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Working with dates before 1970 in MySQL?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 1K+ Views

You need to use date type to work with date before 1970 because date stores value from 1000 to 9999. A date type can be used when you need to work with date part only not for time purpose.MySQL gives the data in the following format. The format is as follows −‘YYYY-MM-DD’The starting date range is as follows −1000-01-01The ending date range is as follows −9999-12-31To understand what we discussed above, let us create two tables. The query to create first table is as follows −mysql> create table DateDemo -> ( -> Id int ...

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How can you implement hit counter to avoid loss of count data with each restart of the application in JSP?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 339 Views

When you restart your application, i.e., web server, this will reset your application variable and your hit counter will reset to zero. To avoid this loss, consider the following points −Define a database table with a single count, let us say hitcount. Assign a zero value to it.With every hit, read the table to get the value of hitcount.Increase the value of hitcount by one and update the table with the new value.Display the new value of hitcount as a total page hit counts.If you want to count hits for all the pages, implement above logic for all the pages.

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The best data type to store 0, 1, null values in MySQL?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 740 Views

You need to use tinyint(1) unsigned NULL to store the value 0, 1 and null values. The syntax is as follows −yourColumnName TINYINT(1) UNSIGNED NULL;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table StoreValue0and1orNULLDemo -> ( -> isDigit TINYINT(1) UNSIGNED NULL -> ); Query OK, 0 rows affected (0.63 sec)Now you can insert records 0, 1, and NULL in the table using insert command. The query is as follows −mysql> insert into StoreValue0and1orNULLDemo values(0); Query OK, 1 row ...

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Does MySQL eliminate common subexpressions between SELECT and HAVING/GROUP BY clause? How to test it?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 144 Views

To test, use the sleep() function.Case 1 −The syntax is as follows −SELECT yourColumnName+sleep(yourIntegerValue) FROM yourTableName GROUP BY yourColumnName+sleep(yourIntegerValue);;Case 2 − You can use another syntax which is as follows −SELECT yourColumnName+sleep(yourIntegerValue) As anyAliasName FROM yourTableName GROUP BY yourAliasName;To understand the above syntaxes, let us create a table. The query to create a table is as follows −mysql> create table sleepDemo    -> (    -> value int    -> ); Query OK, 0 rows affected (1.25 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into sleepDemo values(40); Query OK, 1 row ...

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Multiple Inserts for a single column in MySQL?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 5K+ Views

The syntax for multiple inserts for a single column in MySQL is as follows −INSERT INTO yourTableName(yourColumnName) values(‘yourValue1'), (‘yourValue2'), (‘yourValue3'), (‘yourValue4'), .........N;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table InsertMultipleDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserName varchar(10), -> UserRole varchar(20) -> , -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (3.14 sec)Now you can insert some records in the ...

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JavaTuples setAt2() method for Septet class

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 148 Views

The setAt2() method is used to set the Septet value in JavaTuples and a copy with a new value at the specified index i.e. index 2 here.Let us first see what we need to work with JavaTuples. To work with Septet class in JavaTuples, you need to import the following package −import org.javatuples.Septet;Note − Steps to download and run JavaTuples program If you are using Eclipse IDE to run Septet Class in JavaTuples, then Right Click Project → Properties → Java Build Path → Add External Jars and upload the downloaded JavaTuples jar file.The following is an example −Exampleimport org.javatuples.Septet; ...

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MySQL select dates in 30-day range?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 1K+ Views

To select dates in 30-day range, you can use arithmetic operation - with interval.The syntax is as follows −select *from yourTableName where yourDateColumnName > NOW() - INTERVAL 30 DAY and yourDateColumnName < NOW() + INTERVAL 30 DAY;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectDatesDemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> ArrivalDate datetime    -> ); Query OK, 0 rows affected (0.77 sec)Now you can insert some records in the table using insert command. The query is as ...

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How to remove hyphens using MySQL UPDATE?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 992 Views

To remove hyphens using MySQL update, you can use replace() function. The syntax is as follows −update yourTableName    set yourColumnName=replace(yourColumnName, '-', '' );To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table removeHyphensDemo    -> (    -> userId varchar(100)    -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into removeHyphensDemo values('John-123-456'); Query OK, 1 row affected (0.22 sec) mysql> insert into removeHyphensDemo values('Carol-9999-7777-66555'); Query OK, 1 row affected (0.19 sec) ...

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MySQL select order by acts like a string (not a number)?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 256 Views

You can use the following syntax if your column has varchar data type −select yourColumnName FROM yourTableName ORDER BY yourColumnName +0 DESC;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectOrderdemo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(100),    -> RankNumber varchar(100)    -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into selectOrderdemo(Name, RankNumber) values('Larry', -100); Query OK, 1 row affected (0.23 ...

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