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JDBC Articles
Page 5 of 22
What is the difference between BLOB and CLOB datatypes?
Blob and Clob together are known as LOB(Large Object Type). The following are the major differences between Blob and Clob data types.BlobClobThe full form of Blob is a Binary Large Object.The full form of Clob is Character Large Object.This is used to store large binary data.This is used to store large textual data.This stores values in the form of binary streams.This stores values in the form of character streams.Using this you can stores files like videos, images, gifs, and audio files.Using this you can store files like text files, PDF documents, word documents etc.MySQL supports this with the following datatypes:TINYBLOBBLOBMEDIUMBLOBLONGBLOBMySQL ...
Read MoreHow do you check if a ResultSet is empty or not 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 next() methodThe next() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the next row, from the current position.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.Therefore, ...
Read MoreNot able to save a SAP Crystal Report for Enterprise 4.2
Note that you need to check if Crystal Report for Enterprise 2016 support specific IBM DB2 version and for this you need to check product compatibility guide for development.Are you using Universe developed on IBM DB2 then you need to ensure that you are using correct version of drivers JDBC/ODBC in IDT to create a Relational connection. You also need to ensure that connection is also published to SAP BI repository. If your version of DB2 and Crystal Reports is ok, I would recommend you follow below steps:First steps is to start, you need to create a System DSN in ...
Read MoreHow to escape backslashes in MySQL with JDBC?
To escape backslashes, use PreparedStatement while inserting records. Let us first create a table −mysql> create table DemoTable1904 ( ClientId int, ClientName varchar(20), ClientAge int ); Query OK, 0 rows affected (0.00 sec)The Java code is as follows −import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; public class EscapeBackslashesDemo { public static void main(String[] args) { Connection con = null; PreparedStatement ps = null; try { con = DriverManager.getConnection("jdbc:mysql://localhost:3306/web?" + "useSSL=false", "root", "123456"); String query = "insert into DemoTable1904(ClientId, ...
Read MoreWhere we should close a connection in JDBC and MySQL?
You need to close connection in finally block. Following is the Java code to close connection in JDBC and MySQL −import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.SQLException; public class CloseConnectionDemoInFinallyBlock { public static void main(String[] args) { String JDBCURL = "jdbc:mysql://localhost:3306/web?useSSL=false"; Connection con = null; try { con = DriverManager.getConnection(JDBCURL, "root", "123456"); System.out.println("connection is open"); } catch (Exception e) { e.printStackTrace(); } finally { try { con.close(); } catch (SQLException sqlException) { sqlException.printStackTrace(); } } } }This will produce the following output −connection is openHere is the screenshot of the output −
Read MoreJava ResultSet previous() method with example
When we execute certain SQL queries (SELECT query in general) they return tabular data.The java.sql.ResultSet interface represents such tabular data returned by the SQL statements.i.e. the ResultSet object holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).The ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.The previous() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the previous row, from the current position.This method returns a boolean value specifying whether ...
Read MoreJava ResultSet moveToInsertRow() method with example
When we execute certain SQL queries (SELECT query in general) they return tabular data.The java.sql.ResultSet interface represents such tabular data returned by the SQL statements.i.e. the ResultSet object holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).The ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.The insertRow is a special row of the ResultSet in JDBC, it is associated with the updatable ResultSet objects. In it you can construct a new Row calling the UpdateXXX() ...
Read MoreWhat is ResultSet holdability 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.You can set the ResultSet holdability using the setHoldability() method of the Connection interface.con.setHoldability(ResultSet.CLOSE_CURSORS_AT_COMMIT);The ResultSet interface provides two values to specify the holdability of a ResultSet namely CLOSE_CURSORS_AT_COMMIT and, HOLD_CURSORS_OVER_COMMIT.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), ...
Read MoreJava Connection commit() method with example
The commit() method of the Connection interface saves all the modifications made since the last commit.con.save()If any issue occurs after the commit you can revert all the changes done till this commit by invoking the rollback() method.Con.rollback()To commit a transactionRegister the driver using the registerDriver() method of the DriverManager class as −//Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get the connection using the getConnection() method of the DriverManager class as −//Getting the connection String url = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(url, "root", "password");Turn off the auto-commit using the setAutoCommit() method as −//Setting the auto commit false con.setAutoCommit(false);Commit the transaction using the commit() method as −con.commit();Let us create a table with ...
Read MoreHow can you move the cursor in scrollable result sets in JDBC?
In JDBC there are two scrollable ResultSets namely, scrollable sensitive and, scrollable insensitive.In the TYPE_SCROLL_INSENSITIVE ResultSet the cursor moves in forward or backward directions. This type of ResultSet is insensitive to the changes that are made in the database i.e. the modifications done in the database are not reflected in the ResultSet.Which means if we have established a connection with a database using JDBC program and retrieved a ResultSet holding all the records in a table named SampleTable. Meanwhile if we have added some more records to the table (after retrieving getting the ResultSet), these recent changes will not be reflected ...
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