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Java Articles
Page 387 of 450
How to move the ResultSet cursor to the previous row in JDBC?
Whenever we execute SQL statements using the executeQuery() method, it returns a ResultSet object which holds the tabular data returned by the SELECT queries(in general).The ResultSet object contains a cursor/pointer which points to the current row. Initially this cursor is positioned before first row (default position).You can move the cursor of the ResultSet object to the previous row from the current position, using the previous() method of the ResultSet interface.rs.previous()This method returns a boolean value specifying whether the ResultSet object contains more rows. If there are no rows before its current position this method returns false, else it returns true.Let us ...
Read MoreHow to get all table names from a database using JDBC?
You can get the list of tables in the current database in MySQL using the SHOW TABLES query.Show tables;Following JDBC program retrieves the list of tables in the database by executing the show tables query.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ListingTables { public static void main(String args[]) throws Exception { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Creating a Statement object ...
Read MoreHow to get column count in a ResultSet in JDBC?
You can get the column count in a table using the getColumnCount() method of the ResultSetMetaData interface. On invoking, this method returns an integer representing the number of columns in the table in the current ResultSet object.//Retrieving the ResultSetMetaData object ResultSetMetaData rsmd = rs.getMetaData(); //getting the column type int column_count = rsmd.getColumnCount();Let us create a table with name employee_data in MySQL database using CREATE statement as shown below −CREATE TABLE employee_data( id INT, Name VARCHAR(255), DOB date, Location VARCHAR(40) );Following JDBC program establishes connection with the database, retrieves the ResultSetMetaData object of the employee_data table, and prints the number of columns in it.Exampleimport ...
Read MoreHow to Maintain an open ResultSet after commit in JDBC?
ResultSet holdability determines whether the ResultSet objects (cursors) should be closed or held open when a transaction (that contains the said cursor/ ResultSet object) is committed using the commit() method of the Connection interface.ResultSet interface provides two values to specify the holdability namely CLOSE_CURSORS_AT_COMMIT and HOLD_CURSORS_OVER_COMMITIf the holdability of the ResultSet object is set to this value. Whenever you commit/save a transaction using the commit() method of the Connection interface, the ResultSet objects created in the current transaction (that are already opened) will be held open.Therefore, if you need to hold the ResultSet cursor open after the commit automatically, set ...
Read MoreHow to get the list of all databases using JDBC?
You can get the list of databases in MySQL using the SHOW DATABASES query.show databases;Following JDBC program retrieves the list of databases by executing the show databases query.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ShowDatabasesExample { public static void main(String args[]) throws Exception { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Creating a Statement object Statement stmt = con.createStatement(); ...
Read MoreHow to count rows – count (*) and Java
The SQL Count() function returns the number of rows in a table. Using this you can get the number of rows in a table.select count(*) from TABLE_NAME;Let us create a table with name cricketers_data in MySQL database using CREATE statement as shown below −CREATE TABLE cricketers_data( First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), );Now, we will insert 5 records in cricketers_data table using INSERT statements −insert into cricketers_data values('Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India'); insert into cricketers_data values('Jonathan', 'Trott', DATE('1981-04-22'), 'CapeTown', 'SouthAfrica'); insert into cricketers_data values('Kumara', 'Sangakkara', DATE('1977-10-27'), 'Matale', 'Srilanka'); insert into cricketers_data values('Virat', 'Kohli', DATE('1988-11-05'), 'Delhi', ...
Read MoreHow to get all the column names from a ResultSet using JDBC
You can get the name of a particular column using the getColumnName() method of the ResultSetMetadata interface.This method accepts an integer value representing the index of a column and returns a String value representing the name of the specified column.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), PRIMARY KEY (ID) );Now, we will insert 7 records in MyPlayers table using INSERT statements −insert into MyPlayers values(1, 'Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India'); insert into MyPlayers ...
Read MoreJava ResultSetMetaData getColumnName() method with example
The getColumnName() method of the ResultSetMetaData (interface) retrieves and returns the name of the specified column in the current ResultSet object.This method accepts an integer value representing the index of a column and, returns a String value representing the name of the specified column.To get the ResultSetMetaData object, you need to −Register the Driver: Select the required database register the Driver class of the particular database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get connection: Create a connection object by passing the URL of the database, username and password of a ...
Read MoreHow to get the table name of the current ResultSet using JDBC?
You can get the name of the table in the current ResultSet object using the getTableName() method of the ResultSetMetaData interface. This method accepts an integer value representing the index of a column and, returns a String value representing the name of the table that contains the given column.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), PRIMARY KEY (ID) );Now, we will insert 7 records in MyPlayers table using INSERT statements −insert into ...
Read MoreHow to get the row count from ResultSet in JDBC
Whenever we execute SQL statements using the executeQuery() method, it returns a ResultSet object which holds the tabular data returned by the SELECT queries(in general). The ResultSet object contains a cursor/pointer which points to the current row. Initially this cursor is positioned before first row (default position).The ResultSet interface provides various methods to find, the no.of columns, name of the column, type of the column etc.. but, it does not provides any method to find the number of rows in a table directly.Using count(*) function in the SELECT query you can get the number of rows in a table as −select ...
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