karthikeya Boyini

karthikeya Boyini

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Articles by karthikeya Boyini

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What is contentType attribute in JSP?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 4K+ Views

The contentType attribute sets the character encoding for the JSP page and for the generated response page. The default content type is text/html, which is the standard content type for HTML pages.If you want to write out XML from your JSP, use the following page directive −The following statement directs the browser to render the generated page as HTML −The following directive sets the content type as a Microsoft Word document −You can also specify the character encoding for the response. For example, if you wanted to specify that the resulting page that is returned to the browser uses ISO ...

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MySQL DateTime Now()+5 days/hours/minutes/seconds?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 649 Views

To update the current date and time to 5 days, you need to use the Now() + 5. That would update the entire date-time i.e. days, hour, minutes and seconds. To understand this, let us create a table. The query to create a table is as follows −mysql> create table UserInformationExpire    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> UserName varchar(10),    -> UserInformationExpireDateTime datetime not null    -> ); Query OK, 0 rows affected (0.83 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> ...

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How to group queries using transaction in a JSP?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 328 Views

The tag is used to group the and tags into transactions. You can put as many and tags as statements inside the tag to create a single transaction.It ensures that the database modifications performed by the nested actions are either committed or rolled back if an exception is thrown by any nested action.AttributeThe tag has the following attributes −AttributeDescriptionRequiredDefaultdataSourceDatabase connection to use (overrides the default)NoDefault databaseisolationTransaction isolation (READ_COMMITTED, READ_UNCOMMITTED, REPEATABLE_READ, or SERIALIZABLE)NoDatabase’s defaultExampleTo start with the basic concept, let us create a Students table in the TEST database and create a few records ...

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MySQL find/ replace string in fields?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 381 Views

To find/replace string in fields, the syntax is as follows −update yourTableName set yourColumnName =REPLACE(yourColumnName, yourOldValue, yourNewValue);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table FindReplaceDemo    -> (    -> FileId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> FileDirectory text    -> ); Query OK, 0 rows affected (0.92 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into FindReplaceDemo(FileDirectory) values('C://User//MySQL'); Query OK, 1 row affected (0.19 sec) mysql> insert into FindReplaceDemo(FileDirectory) values('D://WebsiteImage//image1.jpg'); Query OK, ...

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Sum if all rows are not null else return null in MySQL?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 641 Views

You can achieve this with the help of GROUP BY HAVING clause. The syntax is as follows −SELECT yourColumnName1,    SUM(yourCoumnName2)    from yourTableName    GROUP BY yourColumnName1 HAVING COUNT(yourCoumnName2) = COUNT(*);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table SumDemo    -> (    -> Id int,    -> Amount int    -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into SumDemo values(1, 200); Query OK, 1 row affected (0.22 ...

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What is import attribute in JSP?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 2K+ Views

The import attribute serves the same function as and behaves like, the Java import statement. The value for the import option is the name of the package you want to import.To import java.sql.*, use the following page directive −To import multiple packages, you can specify them separated by comma as follows −By default, a container automatically imports java.lang.*, javax.servlet.*, javax.servlet.jsp.*, and javax.servlet.http.*.

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MySQL "order by" inside of "group by"? Is it possible?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 885 Views

Instead of using ORDER BY inside GROUP BY, you can use the MAX() aggregate function.The syntax is as follows −SELECT yourNameColumnName, MAX(yourRankColumnName) FROM yourTableName GROUP BY yourNameColumnName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table MaxDemo    -> (    -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> UserName varchar(20),    -> UserRank int    -> ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into MaxDemo(UserName, UserRank) values('Larry', 2); Query ...

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What is isThreadSafe attribute in JSP?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 2K+ Views

The isThreadSafe option marks a page as being thread-safe. By default, all JSPs are considered thread-safe. If you set the isThreadSafe option to false, the JSP engine makes sure that only one thread at a time is executing your JSP.The following page directive sets the isThreadSafe option to false −

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MySQL select accumulated (running sum) column?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 295 Views

To select accumulated column, let us first create a demo table. The query to create a table is as follows −mysql> create table accumulatedDemo    -> (    -> Value int    -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into accumulatedDemo values(10); Query OK, 1 row affected (0.21 sec) mysql> insert into accumulatedDemo values(15); Query OK, 1 row affected (0.09 sec) mysql> insert into accumulatedDemo values(20); Query OK, 1 row affected (0.13 sec) mysql> insert into accumulatedDemo values(25); Query OK, 1 row affected ...

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Display the warning message when a FLOAT value is inserted into DECIMAL in MySQL?

karthikeya Boyini
karthikeya Boyini
Updated on 30-Jul-2019 204 Views

You can create a temporary table with data type DECIMAL to get a warning when a float value is inserted into an int column. Display the same warning using SHOW WARNINGS.Let us create a table to understand. The query is as follows to create a table.mysql> create temporary table WarningDemo    -> (    -> Value DECIMAL    -> ); Query OK, 0 rows affected (0.13 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into WarningDemo values(9.80); Query OK, 1 row affected, 1 warning (0.03 sec)Here we are getting a warning. Let ...

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