Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles by usharani
Page 5 of 6
While using the ROLLUP modifier, is it possible to use a MySQL ORDER BY clause to sort the result?
Actually ROLLUP and ORDER BY are mutually exclusive in MySQL hence it is not a good practice to use both of them in a query. But still, if we use ROLLUP in ORDER BY then the main disadvantage is that the summary rows would get sorted along with the rows they are calculated. It is also significant to notice that the sort order will decide the position of summary rows.The summary rows would be at the beginning of ascending order and at the end of descending order. Consider the following example to understand it more clearly −mysql> Select * from ...
Read MoreWhat are recursive stored procedures and why MySQL limits the recursion?
A stored procedure is called recursive if it calls itself. Basically, this concept is called recursion. MySQL limits the recursion so the errors will be less rigorous. We can check this limit with the help of the following query −mysql> Show variables LIKE '%recur%'; +------------------------+-------+ | Variable_name | Value | +------------------------+-------+ | max_sp_recursion_depth | 0 | +------------------------+-------+ 1 row in set (0.01 sec)We can change this value up to 255 with the help of the following query −mysql> SET @@GLOBAL.max_sp_recursion_depth = 255// Query OK, 0 rows affected (0.00 sec) mysql> Show variables LIKE ...
Read MoreHow can user variables be used in MySQL stored procedure?
In MySQL stored procedure, user variables are referenced with an ampersand i.e. @, prefixed to the user variable names. For example, @A, @B, etc. are user variables. To demonstrate it, we are creating the following procedure −mysql> DELIMITER // ; mysql> CREATE PROCEDURE Proc_Uservariables() -> BEGIN -> SET @A = 100; -> SET @B = 500; -> SELECT @A,@B,@A+@B; -> END // Query OK, 0 rows affected (0.00 sec) mysql> Delimiter ; // mysql> CALL Proc_Uservariables(); +------+------+-------+ | @A | @B | @A+@B | +------+------+-------+ | 100 | 500 | 600 | +------+------+-------+ 1 row in set (0.00 sec) Query OK, 0 rows affected (0.01 sec)
Read MoreHow to get the MySQL interactive output format in batch mode also?
We can get the MySQL output format in batch mode with the help of –t option. For example, after running the same query in batch mode with –t option we will get the output like interactive format.ExampleC:\Program Files\MySQL\bin>mysql -u root -p gaurav < hh.sql -t Enter password: *****Output+------+ | id | +------+ | 1 | | 2 | +------+
Read MoreHow can INTERSECTION between tables be implemented with the help of MySQL joins?
Actually, INTERSECTION is just an inner join on all columns. We are taking a simple example of two tables, having the data as follows −mysql> Select * from value1; +------+------+ | i | j | +------+------+ | 1 | 1 | | 2 | 2 | +------+------+ 2 rows in set (0.00 sec) mysql> Select * from value2; +------+------+ | i | j | +------+------+ | 1 | 1 | | 3 | 3 | +------+------+ 2 rows in set (0.00 sec)Now, the following query will do the INTERSECTION between these tables −mysql> Select * from value1 join value2 using(i,j); +------+------+ | i | j | +------+------+ | 1 | 1 | +------+------+ 1 row in set (0.08 sec)
Read MoreHow can we import the text file, having some line prefixes, into MySQL table?
Suppose if we have a line prefix in the text file then with the help of using ‘LINES STARTING BY’ option we can ignore that prefix and import correct data into MySQL table. It can be understood with the help of the following example −ExampleSuppose we are using ‘VALUE’ as the ‘LINE PREFIX’ in the text file as follows −id, Name, Country, Salary VALUE:105, Chum*, Marsh, USA, 11000 106, Danny*, Harrison, AUS, 12000Now while importing this text file into MySQL table then we ...
Read MoreException handling with method overriding in Java.
Yes, we can override a method by changing only the exception handling in java pertaining the following rule −An overriding method can throw any unchecked exceptions, regardless of whether the overridden method throws exceptions or not. However, the overriding method should not throw checked exceptions that are new or broader than the ones declared by the overridden method. The overriding method can throw narrower or fewer exceptions than the overridden method.
Read MoreWhat are some frequently used mysqlimport options while uploading the data into MySQL table through command line?
mysqlimport can be run with a number of options. Followings are some options for mysqlimport and their effect on import.OptionAction-r or –replaceCause imported rows to overwrite existing rows if they have the same unique key value.-i or –ignoreIgnore rows that have the same unique key value as existing rows.-f or –forceForce mysqlimport to continue inserting data even if errors are encountered.-l or --lock-tablesLock each table before importing (a good option on a busy server).-d or –deleteEmpty the table before inserting.--fields-terminated- by='char'Specify the separator used between values of the same row, default \t (tab).--fields-enclosed- by='char'Specify the delimiter that encloses each field; ...
Read MoreBreaking out of nested loop in java
Yes, break statement can be used in nested for loops. It works on the for loop in which it is applied. See the example below.Examplepublic class Tester { public static void main(String[] args) { for(int i = 0; i< 2; i++) { for(int j = 0; j < 2; j++){ if(i == 1) { break; } System.out.println("i = " + i+",j = " + j); } } } }
Read MoreHow to create a JAR file?
You can create a JAR file using the following command.jar cf jar-file input-file(s) You can also create JAR files using IDE’s. To create a JAR file using eclipse follow the procedure given below.Open the Jar File wizardThe Jar File wizard can be used to export the content of a project into a jar file. To bring up the Jar File wizard −In the Package Explorer select the items that you want to export. If you want to export all the classes and resources in the project just select the project.Click on the File menu and select Export.In the filter text box ...
Read More