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A JTable is a subclass of JComponent class and it can be used to create a table with information displayed in multiple rows and columns. When a value is selected from a JTable, a TableModelEvent is generated, which is handled by implementing a TableModelListener interface. We can add or insert a radio button to a JTable cell by customizing the TableCellRenderer interface and the DefaultCellEditor class.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.table.*; public class JTableRadioButtonTest extends JFrame { private DefaultTableModel dtm; private ButtonGroup bg; private JTable table; private JScrollPane jsp; public JTableRadioButtonTest() { setTitle("JTableRadioButton Test"); ... Read More
As we know that with the help of SHOW DATABASES statement we can see the list of MySQL databases. Similarly, we can use SHOW SCHEMAS as the synonym of SHOW DATABASES to get the list of databases.Examplemysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | gaurav | | mysql | | performance_schema | | query | | query1 | | sys | | tutorials | +--------------------+ 8 rows in set (0.07 sec) mysql> SHOW SCHEMAS; +--------------------+ | Database | +--------------------+ | information_schema | | gaurav | | mysql | | performance_schema | | query | | query1 | | sys | | tutorials | +--------------------+ 8 rows in set (0.00 sec)
As we know that COALESCE() function returns first non-NULL value from the list of values. The following IF-THEN-ELSE statement is equivalent to COALESCE() function.IF value1 is not NULL THEN output = value1; ELSIF value2 is not NULL THEN output = value2; ELSIF value3 is not NULL THEN output = value3; . . . ELSIF valueN is not NULL THEN output = valueN; ELSE output = NULL; END IF;
If all the values in MySQL COALESCE() function are NULL then it returns NULL as the output. It means that this function does not find any non-NULL value in the list.Examplemysql> Select COALESCE(NULL, NULL, NULL, NULL); +----------------------------------+ | COALESCE(NULL, NULL, NULL, NULL) | +----------------------------------+ | NULL | +----------------------------------+ 1 row in set (0.00 sec)
The syntax of SUBSTRING() function using FROM and FOR keywords is the standard MySQL syntax.SyntaxSUBSTRING(str FROM pos FOR len)Here, str is the string from which substring would be returned.Pos is the starting position of substring.Len is the length of substring i.e. the total number of characters fetched from str.Examplemysql> Select SUBSTRING('foobarbar' FROM 4 FOR 5); +-------------------------------------+ | SUBSTRING('foobarbar' FROM 4 FOR 5) | +-------------------------------------+ | barba | +-------------------------------------+ 1 row in set (0.00 sec)The result set above, makes the use of FROM and FOR keywords very much clear in SUBSTRING() function.
To make it understand, we are using the following data from a table named ‘customerdetail’.mysql> Select * from Customerdetail; +----------------------+----------------------+-----------+---------------------+ | Name | FName | Address | Emailid | +----------------------+----------------------+-----------+---------------------+ | Advik Jhamb | Lovkesh Jhamb | Mumbai | Advik@gmail.com | | Chirag Jai Patil | Raman Jai Patil | Gujrat | chirahp@yahoo.com | | Devansh Singh Rajput | Kishore Singh Rajput ... Read More
MySQL SUBSTRING_INDEX() function can accept the negative value of argument ‘count’ and in this case, it returns the substring from the right of the final delimiter.Examplemysql> Select SUBSTRING_INDEX('www.google.com','.',-2); +------------------------------------------+ | SUBSTRING_INDEX('www.google.com','.',-2) | +------------------------------------------+ | google.com | +------------------------------------------+ 1 row in set (0.00 sec) mysql> Select SUBSTRING_INDEX('www.google.com','.',-1); +------------------------------------------+ | SUBSTRING_INDEX('www.google.com','.',-1) | +------------------------------------------+ | com | +------------------------------------------+ 1 row in set (0.00 sec)
Suppose we have a table named ‘ipaddress’ which contains the IP addresses as its values in column ‘IP’ as follows −mysql> Select * from ipaddress; +-----------------+ | ip | +-----------------+ | 192.128.0.5 | | 255.255.255.255 | | 192.0.255.255 | | 192.0.1.5 | +-----------------+ 4 rows in set (0.10 sec)Now with the help of SUBSTRING_INDEX() function in the following query, we can divide the IP address in four octets −mysql> Select IP, SUBSTRING_INDEX(ip, '.', 1)AS '1st Part', -> SUBSTRING_INDEX(SUBSTRING_INDEX(ip, '.', 2), '.', -1)AS '2nd Part', ... Read More
A JList is a component that can extend JComponent class used to display a list of objects that allows the user to select one or more items.There are three types of selection modes for a JList in JavaListSelectionModel.SINGLE_SELECTION: Only one list index can be selected at a time.ListSelectionModel.SINGLE_INTERVAL_SELECTION: Only one contiguous interval can be selected at a time.ListSelectionModel.MULTIPLE_INTERVAL_SELECTION: In this mode, there is no restriction on what can be selected. This is a default mode.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class JListSelectionModeTest extends JFrame implements ActionListener { private JList list; private DefaultListModel listModel; public JListSelectionModeTest() { ... Read More
With the help of ‘mysqladmin’ along with ‘status’ option program we would be able to check the status of MySQL server. It can be used as follows on command line −C:\mysql\bin>mysqladmin -u root status Uptime: 3865 Threads: 1 Questions: 50 Slow queries: 0 Opens: 113 Flush tables: 1 Open tables: 102 Queries per second avg: 0.012