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JDBC Articles
Page 16 of 22
How to write data into BLOB and CLOB type columns in a table using JDBC?
CLOB stands for Character Large Object. in general, an SQL Clob is a built-in datatype which is used to store large amount of textual data. Using this datatype, you can store data up to 2, 147, 483, 647 characters. MYSQL database provides support Clob datatype TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT.The java.sql.Clob interface of the JDBC API represents the CLOB datatype. Since the Clob object in JDBC is implemented using an SQL locator, it holds a logical pointer to the SQL CLOB (not the data).Inserting Data into a column of Clob typeYou can insert a CLOB type value using the setCharacterStream() or, ...
Read MoreHow to get the list of all drivers registered with the DriverManager using JDBC?
The java.sql.DriverManager class manages JDBC drivers in your application. This class maintains a list of required drivers and load them whenever it is initialized.Therefore, you need to register the driver class before using it. However, you need to do it only once per application.One way to register a driver class object to Driver manager is the registerDriver() method of the DriverManager class. To this method you need to pass the Driver object as a parameter.//Instantiating a driver class Driver driver = new com.mysql.jdbc.Driver(); //Registering the Driver DriverManager.registerDriver(driver);List of all the DriversYou can get the list of all the drivers registered ...
Read MoreHow to insert a DATALINK object into a table using JDBC?
A DATALINK object represents an URL value which refers to an external resource (outside the current database/data source), which can be a file, directory etc.You can store a DATALINK into an SQL table using the setURL() method of the PreparedStatement interface. This method accepts an integer value representing an index of the bind variable, an URL object and, inserts the given URL object in the column represented by the bind variable in the specified index.ExampleLet us create a table with name tutorials_data in MySQL database using CREATE statement as shown below −CREATE TABLE tutorials_data ( tutorial_id INT PRIMARY KEY ...
Read MoreWhat is the use of setFetchSize() and setMaxRows() methods of the JDBC Statement Interface?
The setFetchSize(int) method defines the number of rows that will be read from the database when the ResultSet needs more rows. setFetchSize(int) affects how the database returns the ResultSet data.Whereas, setMaxRows(int) method of the ResultSet specifies how many rows a ResultSet can contain at a time. setMaxRows(int) affects the client side JDBC object.
Read MoreWhat is JDBC Clob data type? how to store and read data from it?
CLOB stands for Character Large Object in general, an SQL Clob is a built-in datatype and is used to store large amount of textual data. Using this datatype, you can store data up to 2, 147, 483, 647 characters.The java.sql.Clob interface of the JDBC API represents the CLOB datatype. Since the Clob object in JDBC is implemented using an SQL locator, it holds a logical pointer to the SQL CLOB (not the data).MYSQL database provides support for this datatype using four variables.TINYTEXT: A CLOB type with a maximum of 28-1 (255) characters.TEXT: A CLOB type with a maximum of 216-1 ...
Read MoreHow to insert data into a CachedRowSet in JDBC? Explain?
The CachedRowSet is the base implementation of disconnected row sets. It connects to the data source, reads data from it, disconnects with the data source and the processes the retrieved data, reconnects to the data source and writes the modifications.Creating a CachedRowSetYou can create a Cached RowSet object using the createCachedRowSet() method of the RowSetFactory.You can create a RowSetFactory object using the newfactory() method of the RowSetProvider method.Create a CachedRowSet object using the above mentioned methods as shown below −//Creating the RowSet object RowSetFactory factory = RowSetProvider.newFactory(); CachedRowSet rowSet = factory.createCachedRowSet();Connecting to the data sourceAfter creating a RowSet object you ...
Read MoreWhat is the difference between execute(), executeQuery() and executeUpdate() methods in JDBC?
Once you have created the statement object you can execute it using one of the execute methods of the Statement interface namely, execute(), executeUpdate() and, executeQuery().The execute() method: This method is used to execute SQL DDL statements, it returns a boolean value specifying weather the ResultSet object can be retrieved.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; public class Example { public static void main(String args[]) throws SQLException { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://localhost/sampleDB"; Connection con = ...
Read MoreIs it mandatory to close JDBC connections?
At the end of your JDBC program, it is required explicitly to close all the connections to the database to end each database session. However, if you forget, Java's garbage collector will close the connection when it cleans up stale objects.Relying on the garbage collection, especially in database programming, is a very poor programming practice. You should make a habit of always closing the connection with the close() method associated with connection object.To ensure that a connection is closed, you could provide a 'finally' block in your code. A finally block always executes, regardless of an exception occurs or not.To ...
Read MoreWhy are Prepared Statements in JDBC faster than Statements? Explain?
While executing statements using Statement object, especially insert statements, each time a query is executed the whole statement is compiled and executed again and again where, the only difference among these statements is the values of the statements.Whereas, prepared statement is a precompiled statement i.e. the query is compiled and stored in the database, using place holders (?) instead of values and values to these place holders are supplied later.Thus, avoiding unnecessary compilation and execution of the statement again and again.ExampleSuppose, we have a table named Dataset in the database with the columns mobile_brand and unit_sale, if we want to ...
Read MoreWhat are the advantages and limitations of JDBC PreparedStatement?
Following are the advantages of the prepared statement:By avoiding multiple compilation and execution of statements, prepared statements perform faster.Using prepared statements, we can insert values to advanced datatypes such as BLOB, CLOB, OBJECT easily with the help of the setter methods provided by the PreparedStatement interface.By providing setter method to set values prepared statement avoids the use of quotes and other special characters with in the query, and thereby it escapes the SQL injection attacksFollowing are the limitations of prepared statements:Since a PreparedStatement object represents only one SQL statement at a time, we can execute only one statement by one ...
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