JDBC Introduction and Architecture
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Questions and Answers

How can you create a Statement object in JDBC?

You need to create a statement using the Connection object's createStatement( ) method.

Which method should be used in JDBC if you expect to get a result set like from a SELECT statement?

  • executeQuery() (correct)
  • executeUpdate()
  • execute()

    • A PreparedStatement object is efficient for repeated executions because SQL statements are ___________.

    precompiled

    In JDBC, you must explicitly ask if a field is null by calling ResultSet.isNull(column).

    <p>True</p> Signup and view all the answers

    Match the following ResultSet methods with their descriptions:

    <p>beforeFirst() = Moves cursor to just before the first row absolute(int row) = Moves cursor to the specified row getString(int columnIndex) = Returns the string in the current row in the specified column index</p> Signup and view all the answers

    What does the 'deleteRow()' method do?

    <p>Deletes the current row from the database.</p> Signup and view all the answers

    Explain the purpose of the 'refreshRow()' method.

    <p>Refreshes the data in the result set to reflect any recent changes in the database.</p> Signup and view all the answers

    What is the functionality of the 'cancelRowUpdates()' method?

    <p>Cancels any updates made on the current row.</p> Signup and view all the answers

    How does the 'insertRow()' method function?

    <p>Inserts a row into the database when the cursor is pointing to the insert row.</p> Signup and view all the answers

    Which JDBC connection method allows creating statements with desired ResultSet?

    <p>createStatement(int RSType, int RSConcurrency)</p> Signup and view all the answers

    What is the purpose of using batch processing in JDBC?

    <p>Executing a group of related statements at once to improve performance.</p> Signup and view all the answers

    Describe the CallableStatement interface in JDBC.

    <p>It is used to execute SQL-stored procedures with IN, OUT, or IN OUT parameters.</p> Signup and view all the answers

    What does JDBC stand for?

    <p>Java Database Connectivity</p> Signup and view all the answers

    Which interface in Java JDBC API manages the loading and unloading of database drivers?

    <p>java.sql.DriverManager</p> Signup and view all the answers

    JDBC driver types include Types 1, 2, 3, and 4.

    <p>True</p> Signup and view all the answers

    To use a JDBC driver, you must first register it with the _______ object.

    <p>DriverManager</p> Signup and view all the answers

    Match the following JDBC driver types with their descriptions:

    <p>JDBC-to-ODBC Bridge Driver = connects Java to a Microsoft ODBC data source Native-API, Part Java Drivers = enable JDBC programs to use database-specific APIs JDBC-Net Pure Java Drivers = translates JDBC requests into a network protocol Native-protocol Pure Java Drivers = connects Java programs directly to a database</p> Signup and view all the answers

    Study Notes

    Introduction to JDBC

    • JDBC (Java Database Connectivity) is a Java API that allows Java programs to access and manipulate data in a database.
    • JDBC is used to connect to a database, execute SQL statements, and retrieve results.

    JDBC Architecture

    • JDBC consists of two parts:
      • JDBC API: a purely Java-based API
      • JDBC Driver Manager: communicates with vendor-specific drivers that interact with the database
    • Translation to vendor format is performed on the client, and no changes are needed on the server.

    JDBC Drivers

    • JDBC drivers implement the defined interfaces in the JDBC API for interacting with a database server.
    • Database vendors and third parties can produce JDBC drivers.
    • There are four types of JDBC drivers:
      • Type 1: JDBC-to-ODBC Bridge Driver
      • Type 2: Native-API, Part Java Drivers
      • Type 3: JDBC-Net Pure Java Drivers
      • Type 4: Native-protocol Pure Java Drivers

    Registering JDBC Drivers

    • To use a JDBC driver, you must register it with the DriverManager object.
    • There are three ways to register a JDBC driver:
      • Using Class.forName(String driverName).newInstance()
      • Using DriverManager.registerDriver(Driver driverName)
      • Using the jdbc.drivers property

    Developing JDBC Programs

    • To develop a JDBC program, you need to:
      1. Load the JDBC driver
      2. Establish a connection to the database
      3. Create a statement
      4. Execute a statement
      5. Process the result set

    Statements

    • The Statement interface provides methods to execute queries with the database.
    • There are three types of statements:
      • Statement: used for simple SQL statements
      • PreparedStatement: used for precompiled SQL statements with parameters
      • CallableStatement: used for stored procedures that may contain both input and output parameters

    Prepared Statements

    • PreparedStatement enables you to create parameterized SQL statements.
    • PreparedStatement objects are created using the prepareStatement method in the Connection interface.
    • You can set parameters using set methods (e.g., setString, setInt) before executing the statement.

    Result Sets

    • A ResultSet object represents the result set of a database query.
    • ResultSet interface methods can be broken down into three categories:
      • Navigational methods: used to move the cursor around
      • Get methods: used to view the data in the columns of the current row
      • Update methods: used to update the data in the columns of the current row### Viewing a Result Set
    • The ResultSet interface contains dozens of methods for getting the data of the current row.
    • There are two versions of each get method: one that takes a column name and one that takes a column index.
    • Examples of get methods include:
      • getInt(String columnName)
      • getInt(int columnIndex)
      • getString(int columnIndex)
      • getBoolean(int columnIndex)
      • getByte(int columnIndex)
      • getShort(int columnIndex)
      • getLong(int columnIndex)
      • getFloat(int columnIndex)
      • getDouble(int columnIndex)
      • getDate(int columnIndex)
      • getTime(int columnIndex)
      • getTimestamp(int columnIndex)

    Updating a Result Set

    • The ResultSet interface contains a collection of update methods for updating the data of a result set.
    • There are two update methods for each data type: one that takes a column name and one that takes a column index.
    • Examples of update methods include:
      • updateString(int columnIndex, String s)
      • updateString(String columnName, String s)
    • Updating a row in the result set changes the columns of the current row in the ResultSet object, but not in the underlying database.
    • To update changes to the row in the database, you need to invoke one of the following methods:
      • updateRow()
      • deleteRow()
      • refreshRow()
      • cancelRowUpdates()
      • insertRow()

    ResultSet Methods

    • isNull(column) checks if a field is null.
    • getMaxRows() and setMaxRows() set the maximum number of rows a ResultSet may contain.

    Creating Statements with Desired ResultSet

    • JDBC provides three methods to create statements with desired ResultSet:
      • createStatement(int RSType, int RSConcurrency)
      • prepareStatement(String SQL, int RSType, int RSConcurrency)
      • prepareCall(String sql, int RSType, int RSConcurrency)

    Type of ResultSet

    • The possible RSType values are:
      • ResultSet.TYPE_FORWARD_ONLY
      • ResultSet.TYPE_SCROLL_INSENSITIVE
      • ResultSet.TYPE_SCROLL_SENSITIVE

    Concurrency of ResultSet

    • The possible RSConcurrency values are:
      • ResultSet.CONCUR_READ_ONLY
      • ResultSet.CONCUR_UPDATABLE

    Batch Processing in JDBC

    • Allows you to group related statements into a batch and submit them with one call to the database.
    • The java.sql.Statement and java.sql.PreparedStatement interfaces provide methods for batch processing.
    • Advantage of batch processing: fast performance.
    • Methods for batch processing:
      • void addBatch(String query)
      • int[] executeBatch()

    CallableStatement

    • The CallableStatement interface is designed to execute SQL-stored procedures.
    • Procedures may have IN, OUT, or IN OUT parameters.
    • Example of a stored procedure in Oracle PL/SQL:
      • create or replace procedure sampleProcedure (p1 in varchar, p2 out number, p3 in out integer) is ...

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    Learn about Java Database Connectivity (JDBC), a Java API that interacts with databases, and its architecture comprising of JDBC API and JDBC Driver Manager.

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