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Articles on Trending Technologies
Technical articles with clear explanations and examples
How can we export data to a CSV file along with columns heading as its first line?
For adding the column values we need to use UNION statement. It can be demonstrated with the help of the following example −ExampleIn this example data from student_info will be exporting to CSV file. The CSV file will have the first line as the name of the columns.mysql>(SELECT 'id', 'Name', 'Address', 'Subject')UNION(SELECT id, Name, Address, Subject From student_info INTO OUTFILE 'C:/mysql/bin/mysql-files/student_25.CSV' FIELDS ENCLOSED BY '"' TERMINATED BY ';' ESCAPED BY '"' LINES TERMINATED BY '\r'); Query OK, 7 rows affected (0.04 sec)After executing the above query MySQL creates Student_25.CSV file which have the following values −id; "Name"; ...
Read MoreHow MySQL evaluates if we export the data to CSV file from a table which contains a NULL value(s)?
If we export the data from a table having NULL values then MySQL will store \N in CSV file for the record MySQL table having NULL values. It can be illustrated with the help of the following example −ExampleSuppose if we want to export the values of the table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 125 | Raman | ...
Read MoreHow can we store any other value than N in CSV file if we export the data to CSV file from a table which contains a NULL value(s)?
If we want to store any other value than \N in CSV file on exporting the data to CSV file from a table which contains NULL value(s) then we need to replace \N values with other value by using IFNULL statement. To illustrate it we are taking the following example −ExampleSuppose if we want to export the values of the table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | ...
Read MoreHow can we tackle MySQL error 'ERROR 1290 (HY000): The MySQL server is running with the --secure-file-priv option so it cannot execute this statement' while importing or exporting the data?
MySQL throws this error because of the two reasons, either no directory is specified under --secure--file--priv variable or we are giving the wrong path in our query while importing or exporting the data. To tackle this error we must have to check the value of –secure—file—priv variable by following query −mysql> Select @@global.secure_file_priv; +---------------------------+ | @@global.secure_file_priv | +---------------------------+ | C:\mysql\bin\mysql-files\ | +---------------------------+ 1 row in set (0.00 sec)We can see there is path under secure_file_priv variable and all the files would be created under this directory when we export the data.But, if the above command shows NULL as result then ...
Read MoreWhich MySQL function returns a specified number of characters of a string as output?
MySQL returns a specified number of characters of a string with the help of LEFT() and RIGHT() functions.MySQL LEFT() function will return the specified number of characters from the left of the string.SyntaxLEFT(str, length)Here str is the string from which a number of characters would be returned and the length is an integer value which specifies how many characters to be returned.Examplemysql> Select LEFT('My Name is Ram', 7); +---------------------------+ | LEFT('My Name is Ram', 7) | +---------------------------+ | My Name | +---------------------------+ 1 row in set (0.00 sec)MySQL RIGHT() function will ...
Read MoreWhy AWT components are heavy-weight while Swing components are light-weight in Java?
AWT stands for Abstract Window ToolKit and it supports Java GUI programming. It is a portable GUI library for Stand-alone Java applications/applets. The AWT provides the connection between our application and the native GUI while Java Swing implements a set of GUI components that build on AWT technology and it can provide a pluggable look and feel. Java Swing is implemented entirely in the Java programming language.First of all, by a heavy-weight, it means the code will take comparatively more time to load and it will consume more System resources. AWT is considered to be heavy-weight because its components are dependent ...
Read MoreWhat is the maximum length of each type of identifier in MySQL?
As we know that certain objects within MySQL are known as identifiers. These objects include a database, table, index, column, alias, view, stored procedure, partition, tablespace etc. Identifiers are stored using Unicode (UTF-8). The maximum length of each type of identifier is given in the following table:Sr. No.IdentifierMaximum Length (characters)1Database642Table643Column644Index645Constraint646Stored Procedure or Function647Trigger648View649Event6410Tablespace6411Log File Group6412Alias25613Compound Statement Label16
Read MoreWhy the constructor name is same as the class name in Java?
Every class object is created using the same new keyword, so it must have information about the class to which it must create an object. For this reason, the constructor name should be the same as the class name.Exampleclass MyConstructor{ public MyConstructor() { System.out.println("The constructor name should be same as the class name"); } public static void main(String args[]){ MyConstructor mc = new MyConstructor(); } }In the above program, the constructor name should be the same as the class name (MyConstructor).OutputThe constructor name should be same as the class name
Read MoreScope and lifetime of variables in Java?
Instance VariablesA variable which is declared inside a class and outside all the methods and blocks is an instance variable. The general scope of an instance variable is throughout the class except in static methods. The lifetime of an instance variable is until the object stays in memory.Class VariablesA variable which is declared inside a class, outside all the blocks and is marked static is known as a class variable. The general scope of a class variable is throughout the class and the lifetime of a class variable is until the end of the program or as long as the ...
Read MoreHow can we use LPAD() or RPAD() functions with the values in the column of a MySQL table?
For using LPAD() or RPAD() functions with the column values we need to specify the column name as the first argument of these functions. Following the example from ‘Student’ table will make it clearer −Examplemysql> Select Name, LPAD(Name, 10, '*') from student; +---------+-------------------+ | Name | LPAD(Name, 10, '*') | +---------+-------------------+ | Gaurav | ****Gaurav | | Aarav | *****Aarav | | Harshit | ***Harshit | | Gaurav | ****Gaurav ...
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