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JDBC Articles
Page 12 of 22
How to move the ResultSet cursor to the next 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 next row from the current position, using the next() method of the ResultSet interface.rs.next()This method returns a boolean value specifying whether the ResultSet object contains more rows.If there are no rows next to its current position this method returns false, else it returns true.Let us create ...
Read MoreHow 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 MoreHow to encrypt a CLOB datatype in JDBC?
Creating an Encrypted LOB(CLOB or, BLOB)Oracle database from 11g onwards provides SecureFiles feature to encrypt the Large object files (LOBs). You can create a secure file using the SECUREFILE keyword as −CREATE TABLE table_name ( myClob CLOB ) LOB(myClob) STORE AS SECUREFILE;You can encrypt a secured file using Encrypt option for encryption you can use 3DES168 or, AES128 or, AES192 or, AES256 algorithm.CREATE TABLE encrypt_tab ( myClob CLOB ) LOB(myClob) STORE AS SECUREFILE encrypt_lob( ENCRYPT USING 'AES256' );
Read MoreHow to determine database type (name) for a given JDBC connection?
One way to get the name of the underlying database you have connected with is by invoking the getDatabaseProductName() method of the DatabaseMetaData interface. This method returns the name of the underlying database in String format.Therefore, to retrieve the name of your current database using Java code −Retrieve the DatabaseMetaData object of the current Connection using the getMetaData() method.//Retrieving the meta data object DatabaseMetaData metaData = con.getMetaData();Then, get the product name of the underlying database you have connected to using the getDatabaseProductName() method of the DatabaseMetaData interface as −//retrieving the name of the database String product_name = metaData.getDatabaseProductName();ExampleFollowing JDBC program ...
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