In 5 Simple Steps - Establish JDBC Connection In Java ~ Amazing News

Click on "Not now, maybe later" link if you do not have an existing account. Step 7) In the next screen, Select color theme of your liking; Click the button "Start Visual Studio'" Step 8) Visual Studio 'Get Started' screen will appear. Create a new project in Visual Studio: Step 1) In the File Menu, Click New > Project . Step 2) In the next screen,Java Database Connectivity (JDBC) is a Java-based data access technology that defines how a client may access a database. It provides methods for querying and updating data in a database. The JDBC classes are contained in the Java package java.sql and javax.sql. Follow the steps to setup a JDBC development environment with which you can […]Extract the zip archive and you will get the jar file. Next, you have to include this jar file into your program so that you will be able to connect your java program with MySQL database. Right-click on the project, go to the properties section then select Java Build Path and click on the Add External JARs button.using create(), Create TCP socket. using bind(), Bind the socket to server address. using listen(), put the server socket in a passive mode, where it waits for the client to approach the server to make a connection; using accept(), At this point, connection is established between client and server, and they are ready to transfer data. Go backBy executing "man ln" command you can see that this says "make link between files" and doesn't say about soft or hard links. [email protected] ~}$ man ln. Similarly the command "man link" describes as "call link function to create a file". Soft-link : Soft link as the name suggests is a just a new link created to the new file.

JDBC MySQL Connection Tutorial - iByteCode Technologies

A single resource adapter is shared between all the sender channels of this option. The details are explained in the following sections. A RFC destination is maintained in the PI system with details of the R/3 system to query the IDOC structure. This connection is created in the section Step-1Use Transaction SM59 to create the RFC Connection. Expand TCP/IP Connection, then Select Create. The Program ID is the one which you have already created in DS Management Console. Then once you click the Connection Test button you should see the message Connection Successful.Step 1. Move "C: \Program Files" fodler to "D: \Program Files". Step 2. Type cmd in the search box, click it and run as administrator. Step 3. Create a symbolic link with soft link mklink/D link target. To move the whole "C: Program Files" folder to "D: Program Files" folder, you need to type the following in the command prompt window.To run a unix based shell script as a concurrent program, the executable of the concurrent program should be registered as a 'Host' program. The execution file name of the host program should end with .prog extension and a soft link should be created for the .prog file. Here is an example of creation of host program with one parameter: Step 1:

How to Connect MySQL Database in Java using Eclipse Step

Connection con = DriverManager.getConnection(url,user,password) user - username from which your sql command prompt can be accessed. password - password from which your sql command prompt can be accessed.. con: is a reference to Connection interface. url : Uniform Resource Locator.It can be created as follows: String url = " jdbc:oracle:thin:@localhost:1521:xe"Which step creates a connection between a file and a program? a. Open the file. b. Read the file. c. Process the file. Closing a file disconnects the communication between the file and the program. False. True/False: Python allows the programmer to work with text and number files. It is possible to create a while loop that determinesRegister RFC Program ID. This step is usually performed by the BASIS team when setting up the system. Program ID is registered either in saprfc.ini file or using the program interface in rfclib. Get assistance from your BASIS team for this task. Learn how to register the program ID using saprfc.ini file here. Create RFC DestinationThis program uses the successful file created by the preliminary DME program. It produces a Payment Summary, a DME Accompanying Sheet, and a DME File (per company code) for each paying bank. The DME File may need to be uploaded into designated software that enables a bank transfer between your company and your paying bank.Which step creates a connection between a file and a program? Open the file True/False: If the last line in a file is not terminated with a \n the readline method will return without a \n.

This chapter is from the e-book 

Fundamental Steps in JDBC

The fundamental steps involved within the strategy of connecting to a database and executing a question consist of the next:

Import JDBC applications.

Load and sign in the JDBC driver.

Open a connection to the database.

Create a statement object to accomplish a query.

Execute the remark object and go back a query resultset.

Process the resultset.

Close the resultset and statement objects.

Close the connection.

These steps are described intimately within the sections that practice.

Import JDBC Packages

This is for making the JDBC API classes instantly available to the application program. The following import statement must be incorporated within the program regardless of the JDBC driver being used:

import java.sql.*;

Additionally, depending on the options getting used, Oracle-supplied JDBC programs might need to be imported. For instance, the next programs might need to be imported while using the Oracle extensions to JDBC equivalent to the use of complex knowledge varieties corresponding to BLOB, and so on.

import oracle.jdbc.driver.*; import oracle.sql.*; Load and Register the JDBC Driver

This is for establishing a communication between the JDBC program and the Oracle database. This is finished by means of the use of the static registerDriver() approach of the DriverSupervisor class of the JDBC API. The following line of code does this job:

DriverSupervisor.sign inDriver(new oracle.jdbc.motive force.OracleDriver());

JDBC Driver Registration

For all the Java utility, the JDBC motive force is registered only as soon as in keeping with each database that needs to be accessed. This is right even if there are more than one database connections to the similar data server.

Alternatively, the forName() manner of the java.lang.Class elegance can be utilized to load and check in the JDBC driving force:

Class.forName("oracle.jdbc.driver.OracleDriver");

However, the forName() way is valid for only JDK-compliant Java Virtual Machines and implicitly creates an instance of the Oracle driving force, while the sign inDriver() way does this explicitly.

Connecting to a Database

Once the required programs have been imported and the Oracle JDBC driver has been loaded and registered, a database connection will have to be established. This is accomplished by means of the use of the getConnection() way of the DriverManager magnificence. A call to this technique creates an object instance of the java.sql.Connection elegance. The getConnection() calls for three input parameters, namely, a attach string, a username, and a password. The connect string should specify the JDBC driver to be sure and the database example to hook up with.

The getConnection() manner is an overloaded method that takes

Three parameters, one every for the URL, username, and password.

Only one parameter for the database URL. In this case, the URL incorporates the username and password.

The following traces of code illustrate the usage of the getConnection() method:

Connection conn = DriverManager.getConnection(URL, username, passwd); Connection conn = DriverManager.getConnection(URL);

the place URL, username, and passwd are of String information types.

We will talk about the methods of opening a connection using the Oracle JDBC OCI and thin _drivers.

When using the OCI driver, the database can also be specified the use of the TNSNAMES entry within the tnsnames.ora file. For instance, to hook up with a database on a particular host as person oratest and password oratest that has a TNSNAMES entry of oracle.world, use the next code:

Connection conn = DriverManager.getConnection("jdbc:oracle:oci8: @oracle.world", "oratest", "oratest");

Both the ":" and "@" are mandatory.

When using the JDBC skinny driver, the TNSNAMES entry can't be used to identify the database. There are two ways of specifying the connect string in this case, particularly,

Explicitly specifying the hostname, the TCP/IP port number, and the Oracle SID of the database to connect to. This is for skinny driving force simplest.

Specify a Net8 keyword-value pair record.

For instance, for the express manner, use the following code to hook up with a database on host training where the TCP/IP listener is on port 1521, the SID for the database example is Oracle, the username and password are each oratest:

Connection conn = DriverManager.getConnection ("jdbc:oracle:thin:@training:1521:Oracle", "oratest", "oratest");

For the Net8 keyword-value pair record, use the following:

Connection conn = DriverManager.getConnection ("jdbc:oracle:thin@(description=(address= (host=training)(protocol=tcp)(port=1521)) (connect_data=(sid=Oracle))) ", _"oratest", "oratest");

This means may also be used for the JDBC OCI driving force. Just specify oci8 as a substitute of thin within the above keyword-value pair list.

Querying the Database

Querying the database comes to two steps: first, growing a remark object to perform a question, and 2d, executing the query and returning a resultset.

Creating a Statement Object

This is to instantiate items that run the question towards the database hooked up to. This is finished by means of the createStatement() approach of the conn Connection object created above. A call to this system creates an object instance of the Statement magnificence. The following line of code illustrates this:

Statement sql_stmt = conn.createStatement(); Executing the Query and Returning a ResultSet

Once a Statement object has been constructed, the following step is to execute the question. This is finished by means of using the executeQuery() manner of the Statement object. A decision to this technique takes as parameter a SQL SELECT remark and returns a JDBC ResultSet object. The following line of code illustrates this using the sql_stmt object created above:

ResultSet rset = sql_stmt.executeQuery ("SELECT empno, ename, sal, deptno FROM emp ORDER BY ename");

Alternatively, the SQL statement will also be positioned in a string and then this string passed to the executeQuery() serve as. This is proven below.

String sql = "SELECT empno, ename, sal, deptno FROM emp ORDER BY ename"; ResultSet rset = sql_stmt.executeQuery(sql);

Statement and ResultSet Objects

Statement and ResultSet items open a corresponding cursor within the database for SELECT and other DML statements.

The above statement executes the SELECT statement specified in between the double quotes and shops the ensuing rows in an instance of the ResultSet object named rset.

Processing the Results of a Database Query That Returns Multiple Rows

Once the query has been achieved, there are two steps to be carried out:

The first step is completed the use of the following() means of the ResultSet object. A call to subsequent() is carried out in a loop to fetch the rows one row at a time, with every call to subsequent() advancing the regulate to the following available row. The next() method returns the Boolean cost true whilst rows are still available for fetching and returns false when the entire rows had been fetched.

The second step is finished by using the getXXX() strategies of the JDBC rset object. Here getXXX() corresponds to the getInt(), getString() etc with XXX being changed via a Java datatype.

The following code demonstrates the above steps:

String str; while (rset.next()) str = rset.getInt(1)+ " "+ rset.getString(2)+ " "+rset.getFloat(3)+ " "rset.getInt(4)+ "\n"; byte buf[] = str.getBytes(); OutputStream fp = new FileOutputStream("query1.lst"); fp.write(buf); fp.close();

Here the 1, 2, 3, and 4 in rset.getInt(), rset.getString(), getFloat(), and getInt() respectively denote the location of the columns in the SELECT observation, that is, the first column empno, 2nd column ename, third column sal, and fourth column deptno of the SELECT remark respectively.

Specifying get() Parameters

The parameters for the getXXX() methods can be specified by place of the corresponding columns as numbers 1, 2, and so on, or by means of without delay specifying the column names enclosed in double quotes, as getString("ename") and so on, or a combination of both.

Closing the ResultSet and Statement

Once the ResultSet and Statement objects were used, they will have to be closed explicitly. This is done by calls to the close() way of the ResultSet and Statement classes. The following code illustrates this:

rset.shut(); sql_stmt.shut();

If not closed explicitly, there are two disadvantages:

Closing the ResultSet and Statement gadgets frees the corresponding cursor in the database.

Closing the Connection

The closing step is to close the database connection opened at first after uploading the packages and loading the JDBC drivers. This is finished by means of a call to the shut() manner of the Connection magnificence.

The following line of code does this:

conn.shut();

Explicitly Close your Connection

Closing the ResultSet and Statement gadgets does not shut the connection. The connection should be closed by explicitly invoking the close() approach of the Connection magnificence.

A complete instance of the above procedures the use of a JDBC skinny driving force is given below. This program queries the emp desk and writes the output rows to an operating gadget file.

//Import JDBC package import java.sql.*; // Import Java bundle for File I/O import java.io.*; public elegance QueryInstance public static void main (String[] args) throws SQLException, IOException //Load and register Oracle driver DriverManager.sign upDriver(new oracle.jdbc.driver.OracleDriver()); //Establish a connection Connection conn = DriverManager.getConnection("jdbc:oracle:thin: @training:1521:Oracle", "oratest", "oratest"); //Create a Statement object Statement sql_stmt = conn.createStatement(); //Create a ResultSet object, execute the query and go back a // resultset ResultSet rset = sql_stmt.executeQuery("SELECT empno, ename, sal, deptno FROM emp ORDER BY ename"); //Process the resultset, retrieve knowledge in every row, column by way of column //and write to an running gadget file String str = ""; while (rset.next()) str += rset.getInt(1)+" "+ rset.getString(2)+" "+ rset.getFloat(3)+" "+rset.getInt(4)+"\n"; byte buf[] = str.getBytes(); OutputStream fp = new FileOutputStream("query1.lst"); fp.write(buf); fp.shut(); //Close the ResultSet and Statement rset.close(); sql_stmt.shut(); //Close the database connection conn.close(); Processing the Results of a Database Query That Returns a Single Row

The above sections and the complete example explained the processing of a query that returned more than one rows. This phase highlights the processing of a single-row query and explains learn how to write code that's the analogue of the PL/SQL exception NO_DATA_FOUND.

NO DATA FOUND Exception

NO_DATA_FOUND exception in PL/SQL is simulated in JDBC by way of using the return cost of the following() approach of the ResultSet object. A price of false returned through the following() way identifies a NO_DATA_FOUND exception.

Consider the next code (this uses the ResultSet object rset explained in the above sections):

if (rset.subsequent()) // Process the row returned else System.out.println("The Employee with Empno "+ args[1] + "does not exist");

Instead of the while loop used earlier, an if statement is used to resolve whether the SELECT remark returned a row or not.

Datatype Mappings

Corresponding to every SQL knowledge sort, there exist mappings to the corresponding JDBC Types, same old Java sorts, and the Java sorts provided by way of Oracle extensions. These are required for use in JDBC programs that manipulate data and information buildings according to those types.

There are four categories of Data sorts any of which can also be mapped to the others. These are:

SQL Data types—These are Oracle SQL data types that exist in the database.

JDBC Typecodes—These are the data typecodes supported via JDBC as explained in the java.sql.Types class or explained via Oracle in oracle.jdbc.motive force.OracleTypes class.

Java Types—These are the standard types explained in the Java language.

Oracle Extension Java Types—These are the Oracle extensions to the SQL data sorts and are explained within the oracle.sql.* class. Mapping SQL knowledge types to the oracle.sql.* Java types enables garage and retrieval of SQL data without first changing into Java format thus preventing any loss of information.

Table 3.1 lists the default mappings current between those four different types.

Table 3.1 Standard and Oracle-specific SQL-Java Data Type Mappings

SQL Data varieties

JDBC Type codes

Standard Java Types

Oracle Extension Java _ Types

Standard JDBC 1.0 Types

CHAR

java.sql.Types.CHAR

java.lang.String

oracle.sql.CHAR

VARCHAR2

java.sql.Types.VARCHAR

java.lang.String

oracle.sql.CHAR

LONG

java.sql.Types. LONGVARCHAR

java.lang.String

oracle.sql.CHAR_

NUMBER

java.sql.Types.NUMERIC

java.math.BigDecimal

oracle.sql.NUMBER

NUMBER

java.sql.Types.DECIMAL

java.math.BigDecimal

oracle.sql.NUMBER

NUMBER

java.sql.Types.BIT

Boolean

oracle.sql.NUMBER

NUMBER

java.sql.Types.TINYINT

byte

oracle.sql.NUMBER

NUMBER

java.sql.Types.SMALLINT

quick

oracle.sql.NUMBER

NUMBER

java.sql.Types.INTEGER

int

oracle.sql.NUMBER

NUMBER

java.sql.Types.BIGINT

lengthy

oracle.sql.NUMBER

NUMBER

java.sql.Types.REAL

flow

oracle.sql.NUMBER

NUMBER

java.sql.Types.FLOAT

double

oracle.sql.NUMBER

NUMBER

java.sql.Types.DOUBLE

double

oracle.sql.NUMBER

RAW

java.sql.Types.BINARY

byte[]

oracle.sql.RAW

RAW

java.sql.Types.VARBINARY

byte[]

oracle.sql.RAW

LONGRAW

java.sql.Types.LONGVARBINARY

byte[]

oracle.sql.RAW

DATE

java.sql.Types.DATE

java.sql.Date

oracle.sql.DATE

DATE

java.sql.Types.TIME

java.sql.Time

oracle.sql.DATE

DATE

java.sql.Types.TIMESTAMP

javal.sql.Timestamp

oracle.sql.DATE

Standard JDBC 2.0 Types

BLOB

java.sql.Types.BLOB

java.sql.Blob

Oracle.sql.BLOB

CLOB

Java.sql.Types.CLOB

java.sql.Clob

oracle.sql.CLOB

user-defined

java.sql.Types.STRUCT

java.sql.Struct

oracle.sql.STRUCT_object

user-defined

java.sql.Types.REF

java.sql.Ref

oracle.sql.REF_reference

user-defined

java.sql.Types.ARRAY

java.sql.Array

oracle.sql.ARRAY_collection

Oracle Extensions

BFILE

oracle.jdbc.driving force.

oracle.sql.BFILE_

n/a

OracleTypes.BFILE

ROWID

oracle.jdbc.driver. oracle.sql.ROWID_

n/a

OracleTypes.ROWID

REFCURSOR kind

oracle.jdbc.motive force. OracleTypes.CURSOR

java.sql.ResultSet

oracle.jdbc.motive force._

OracleResultSet

Exception Handling in JDBC

Like in PL/SQL methods, exceptions do occur in JDBC techniques. Notice how the NO_DATA_FOUND exception was once simulated within the previous segment "Processing the Results of a Database Query That Returns a Single Row."

Exceptions in JDBC are usually of 2 sorts:

Just as PL/SQL provides for an implicit or specific RAISE observation for an exception, Oracle JDBC programs have a throw remark this is used to inform that JDBC calls throw the SQL exceptions. This is shown underneath.

throws SQLException

This creates circumstances of the class java.sql.SQLException or a subclass of it.

And, like in PL/SQL, SQL exceptions in JDBC need to be handled explicitly. Similar to PL/SQL exception handling sections, Java supplies a check out..catch segment that may care for all exceptions together with SQL exceptions. Handling an exception can mainly include retrieving the error code, error textual content, the SQL state, and/or printing the error stack trace. The SQLException class supplies methods for obtaining all of this data in case of error conditions.

Retrieving Error Code, Error Text, and SQL State

There are the methods getErrorCode() and getMessage() very similar to the purposes SQLCODE and SQLERRM in PL/SQL. To retrieve the SQL state, there may be the process getSQLState(). A brief description of these strategies is given under:

getErrorCode()

This serve as returns the five-digit ORA choice of the mistake in case of exceptions happening within the JDBC motive force in addition to within the database.

getMessage()

This serve as returns the error message textual content in case of exceptions occurring in the JDBC driver. For exceptions occurring in the database, this function returns the mistake message textual content prefixed with the ORA quantity.

getSQLState()

This function returns the 5 digit code indicating the SQL state simplest for exceptions happening in the database.

The following code illustrates using exception handlers in JDBC:

take a look at <JDBC code> catch (SQLException e) System.out.println("ERR: "+ e.getMessage())

We now display the QueryInstance elegance of the sooner phase with whole exception handlers built in it. The code is as follows:

//Import JDBC package import java.sql.*; // Import Java package for File I/O import java.io.*; public elegance QueryInstance public static void major (String[] args) int ret_code; try //Load and sign in Oracle driving force DriverManager.sign inDriver(new oracle.jdbc.driver.OracleDriver()); //Establish a connection Connection conn = DriverManager.getConnection("jdbc:oracle:thin: @training:1521:Oracle", "oratest", "oratest"); //Create a Statement object Statement sql_stmt = conn.createStatement(); //Create a ResultSet object, execute the query and go back a // resultset ResultSet rset = sql_stmt.executeQuery("SELECT empno, ename, sal, deptno FROM emp ORDER BY ename"); //Process the resultset, retrieve knowledge in each and every row, column by column // and write to an operating gadget file String str = ""; whilst (rset.subsequent()) str += rset.getInt(1)+" "+ rset.getString(2)+" "+rset.getFloat(3)+ " "+rset.getInt(4)+"\n"; byte buf[] = str.getBytes(); OutputStream fp = new FileOutputStream("query1.lst"); fp.write(buf); fp.close(); //Close the ResultSet and Statement rset.shut(); sql_stmt.shut(); //Close the database connection conn.shut(); catch (SQLException e) ret_code = e.getErrorCode(); System.err.println("Oracle Error: "+ ret_code + e.getMessage()); catch (IOException e) System.out.println("Java Error: "+ e.getMessage()); Printing Error Stack Trace

The SQLException has the process printStackTrace() for printing an error stack hint. This way prints the stack trace of the throwable object to the standard error flow.

The following code illustrates this:

catch (SQLException e) e.printStackTrace();