Jsp buffer and autoFlush - Refresh

 

<%@ page buffer=sizekb %>

Gives the size of the page buffer in kb or none for no buffer. Default 8kb. If buffer is none, all output is immediately flushed.

JSP 1.0 gives page writers flexibility by buffering its output before sending the response to HTTP. The buffering allows error recovery and forwarding, even after generating some content. Once the buffer has filled, it will be flushed. So applications must still detect their errors early.

The following example generates an XML section (for variety). If the form's query is missing the 'name' parameter, it will redirect the results.

<?xml version='1.0'?>           <form>           <%           if (request.form["name"] == null)           pageContext.forward("redo-form.jsp");             for (var name in request.form) {           out.print("<" + name + ">");           out.print(request.form[name]);           out.println("</" + name + ">");           }           %>           </form>

<%@ page autoFlush="true" %>

Tells JSP to flush the page buffer when it fills. Default is true.

If autoFlush is false, the JSP engine will throw an exception if the buffer overflows.

 

Jsp and Html Comments

JSP and HTML Comments

In a jsp we should always try to use jsp- style comments unless you want the comments to appear in the HTML. Jsp comments are converted by the jsp engine into java comments in the source code of the servlet that implements the Jsp page. The jsp comment don't appear in the output produced by the jsp page when it runs. Jsp comments do not increase the size of the file,  jsp page are useful to increase the readability of the jsp page.

In Jsp two types of comments are allowed in the Jsp page:

1) Hidden comment: This comment will not appear in the output.

<%-- Hidden comment --%>

2) Output comment: This type of comment will appear in the output.

<!-- Output comment>

 

 

JSP - Not to Cache Jsp page in browser

 

JSP – Not to Cache Jsp page

 

<%

response.setHeader("Pragma","No-cache");

response.setHeader("Cache-Control","no-cache");

response.setHeader("Cache-Control","no-store" );

 

%>

 

Oracle DEFINE Command

Using the DEFINE Command with& Substitution Variable

 

Syntax:

 

 

 

Step 1:

 

Create the substitution variable using the DEFINE

command.

 

DEFINE employee_num = 200

 

 

Step 2:

Use a variable prefixed with an ampersand (&) to substitute the value in the SQL statement.

SELECT employee_id, last_name, salary, department_id

FROM employees

WHERE employee_id = &employee_num ;

 

Oracle Constraints.(you might be knowing...just for refresh)

Oracle Constraints…

 

 

We can add, drop, enable and disable constraints in the Oracle…

 

 

Syntax for adding a constraint..

 

ALTER TABLE table

ADD [CONSTRAINT constraint] type (column);

 

 

e.g.

 

ALTER TABLE EMPLOYEE

ADD CONSTRAINT emp_manager_fk

FOREIGN KEY(manager_id) REFERENCES employee(employee_id)

 

 

 

Syntax for dropping a constraint…

 

 

ALTER TABLE EMPLOYEE

DROP CONSTRAINT emp_manager_fk

 

 

 

 

Syntax for enabling and disabling a constraint…

 

ALTER TABLE EMPLOYEE

DISABLE CONSTRAINT emp_manager_fk

 

ALTER TABLE EMPLOYEE

ENABLE  CONSTRAINT emp_manager_fk

 

 

 

 

Call stored procedures with IN, OUT, and IN/OUT parameters.

his example demonstrates how to call stored procedures with IN, OUT, and IN/OUT parameters.

    CallableStatement cs;

    try {

      // Call a procedure with no parameters

        cs = connection.prepareCall("{call myproc}");

        cs.execute();

     // Call a procedure with one IN parameter

        cs = connection.prepareCall("{call myprocin(?)}");

        // Set the value for the IN parameter

        cs.setString(1, "a string");

        // Execute the stored procedure

        cs.execute();

     // Call a procedure with one OUT parameter

        cs = connection.prepareCall("{call myprocout(?)}");

        // Register the type of the OUT parameter

        cs.registerOutParameter(1, Types.VARCHAR);

        // Execute the stored procedure and retrieve the OUT value

        cs.execute();

        String outParam = cs.getString(1);     // OUT parameter

    // Call a procedure with one IN/OUT parameter

        cs = connection.prepareCall("{call myprocinout(?)}");

        // Register the type of the IN/OUT parameter

        cs.registerOutParameter(1, Types.VARCHAR);

        // Set the value for the IN/OUT parameter

        cs.setString(1, "a string");

        // Execute the stored procedure and retrieve the IN/OUT value

        cs.execute();

        outParam = cs.getString(1);            // OUT parameter

    } catch (SQLException e) {

    }

 

 

 

FW: Simple Stored Procedure and How to call from Java

Simple Oracle Procedure:

 

create procedure set_death_age(poet VARCHAR2, poet_age NUMBER)

    poet_id NUMBER;

begin

  SELECT id INTO poet_id FROM poets WHERE name = poet;

  INSERT INTO deaths (mort_id, age) VALUES (poet_id, poet_age);

end set_death_age;

 

 

 

Calling simple procedure from Java

 

   Connection con = null;

   CallableStatement proc = null;

   try

   {

      con  = connectionPool.getConnection();

      proc = con.prepareCall("{ call set_death_age(?, ?) }");

      proc.setString(1, dyingBard.getName());

      proc.setInt(2, age);

      proc.execute();

   }

   finally

   {

      try

      {

         proc.close();

      }

      catch (SQLException e) {}

      con.close();

   }

 

Synonyms - Oracle

Synonyms

 

 

Simplify access to objects by creating a synonym (another name for an object). With synonyms, you can:

 

• Ease referring to a table owned by another user

• Shorten lengthy object names

 

Query syntax

 

CREATE [PUBLIC] SYNONYM synonym

FOR object;

Eg:

CREATE PUBLIC SYNONYM dept

FOR alice.departments;

 

To find out Date, Time and Characterset format of Oracle server.

To find out Date, Time and Characterset format of Oracle server.

 

 

select * from v$nls_parameters;

 

 

 

 

NLS_LANGUAGE                                                     AMERICAN                                                        

NLS_TERRITORY                                                    AMERICA                                                          

NLS_CURRENCY                                                     $                                                               

NLS_ISO_CURRENCY                                                 AMERICA                                                          

NLS_NUMERIC_CHARACTERS                                           .,                                                              

NLS_CALENDAR                                                     GREGORIAN                                                        

NLS_DATE_FORMAT                                                  DD-MON-RR                                                       

NLS_DATE_LANGUAGE                                                AMERICAN                                                        

NLS_CHARACTERSET                                                 UTF8                                                            

NLS_SORT                                                         BINARY                                                          

NLS_TIME_FORMAT                                                  HH.MI.SSXFF AM                                                  

NLS_TIMESTAMP_FORMAT                                             DD-MON-RR HH.MI.SSXFF AM                                        

NLS_TIME_TZ_FORMAT                                               HH.MI.SSXFF AM TZR                                              

NLS_TIMESTAMP_TZ_FORMAT                                          DD-MON-RR HH.MI.SSXFF AM TZR                                    

NLS_DUAL_CURRENCY                                                $                                                               

NLS_NCHAR_CHARACTERSET                                           AL16UTF16                                                       

NLS_COMP                                                         BINARY                                                          

NLS_LENGTH_SEMANTICS                                             BYTE                                                            

NLS_NCHAR_CONV_EXCP                                              FALSE                                                           

 

formdef.plugin.util.FormUtils-------Automating Conversion from Action Form to Java Business Objects/Value Objects

FormUtils.setFormValues()

    FormUtils.setFormValues() can be used to initialize a form bean with values from a business object:

    DynaActionForm dynaForm = (DynaActionForm) 

            FormDefUtil.setFormValues("employeeForm", employee,

                    this, mapping, request);

The first parameter identifies the form definition that will be used.
The second parameter is the business object which contains the values that will be used to populate the form bean.
The last three parameters are the current Action object, the current action mapping, and the request being processed.

FormUtils.setFormValues() returns the populated form bean. This can then be placed by the caller in the proper scope with the proper name so that Struts can find it when rendering an HTML form.

 

  FormUtils.getFormValues()

    FormUtils.getFormValues() can be used to create a populated business object from a form bean:

    Employee employee = (Employee)

            FormDefUtil.getFormValues(form, this, mapping, request);

The first parameter is the form passed by Struts to the action object.
The next three parameters are the current Action object, the current action mapping, and the request being processed.

getFormValues() returns the business object populated with values from the form bean. If a factory is associated with the form definition, it is called to create the business object that will be populated. Otherwise, the business object's no-arg constructor will be used to create the object.

What is a foreign key?

What is a foreign key?

A foreign key means that values in one table must also appear in another table.

The referenced table is called the parent table while the table with the foreign key is called the child table. The foreign key in the child table will generally reference a primary key in the parent table.

A foreign key can be defined in either a CREATE TABLE statement or an ALTER TABLE statement.

 

Using a CREATE TABLE statement

The syntax for creating a foreign key using a CREATE TABLE statement is:

CREATE TABLE table_name
(column1 datatype null/not null,
column2 datatype null/not null,
...
CONSTRAINT fk_column
  FOREIGN KEY (column1, column2, ... column_n)
  REFERENCES parent_table (column1, column2, ... column_n)
);

 

For example:

CREATE TABLE supplier
(	supplier_id	numeric(10)	not null,
	supplier_name	varchar2(50)	not null,
	contact_name	varchar2(50),
	CONSTRAINT supplier_pk PRIMARY KEY (supplier_id)
);

 

CREATE TABLE products
(	product_id	numeric(10)	not null,
	supplier_id	numeric(10)	not null,
	CONSTRAINT fk_supplier
	FOREIGN KEY (supplier_id)
	REFERENCES supplier(supplier_id)
);

In this example, we've created a primary key on the supplier table called supplier_pk. It consists of only one field - the supplier_id field. Then we've created a foreign key called fk_supplier on the products table that references the supplier table based on the supplier_id field.

Putting text on the status bar

Putting text on the status bar

example demonstrates how to manipulate text on the status bar. When you move the cursor over a hyperlink, the statusbar shows the destination URL. This is not very helpful. Fortunately, it is very easy to put our own brief description there.

The normal HTML code for a hyperlink might be something like this:

<A HREF="mylink.htm">Click here</A>

To display something on the status bar when the mouse is moved over this link, you need to add a little more:

<A HREF="mylink.htm" onMouseOver="window.status='Click
here to know more about me'; return true;" onMouseOut="window.status=''; ">Click here</A>

 

Simple query to find out the version of Oracle..

Simple query to find out the version of Oracle..

Select * from v$version;

what is Oracle Schema

Schema

 

 

A schema is a collection of objects, such as tables, views, database user and has the same name as that user.

 

 

Check this link for more info

http://www.oracle.com/technology/obe/2day_dba/schema/schema.htm#t1