Examples:
content_tag(:div, "Hello Rails!")
   # => Hello Rails!
content_tag(:div, content_tag(:p, "How Are You?"), :class => "status_msg")
   # =>  <div class="status_msg"><p>How Are You?</p></div>

<% content_tag :span, :class => "side_footer" do -%>
    I love Rails!
<% end -%>

def user_navigation_bar
 content_tag(:div, :class =>"top_banner") do
   if current_user
     content_tag(:li) { current_user.username}
     content_tag(:li) { link_to("Edit Profile", edit_user_path(:current)) }
     content_tag(:li) { link_to("Logout", logout_path) }
   else
     content_tag(:li) { link_to("Login", login_path) }
     content_tag(:li) { link_to("Signup", new_user_path) }
   end
  end
end

So, i always need to explore the places( historical buildings, colleges for exams, markets for shopping etc.). But i always found Atlas has very limited information which i want. Sometimes i need to consult with delhities (delhi’s localized people) for awareness of any place.

I was always very thankful of google to launch google maps.It was a wonderful place for exploring places anywhere in the world. With google maps, i can wonderfully zoom the maps for close look, can search nearby places, can see street views etc, some images of popular images with markers on the map.So, purpose of google map has always been to help the people to find information easily without exploring the whole web.
Last week google launched Google Place Pages on google maps.A Place Page is a web page for every place in the world, organizing all the world’s information for that place.There are Place Pages for businesses, historical places, points of interest, stations and airports, landmarks, and cities all over the world.

Now we can get to a Place Page by just clicking on “more info >>“ in search results, or by clicking “more info” in

the mini-bubble.

Here one can find Photos & Videos, popular places , map image with marker pointing to your location, reviews by other visitors etc.

But there are some questions in my mind after seeing this enhancement made by google -

1.   Is google trying to resisting the visitors to navigate to other related travel site where one can found this

information?

2.   Will this enhancement be able to increase the revenue of google adwords by clicking the add on the google Place

page directly and not to any other related site ?

3.   Can ‘Place Page’ really affect the tours n travels guides websites and hence decrease their traffic and business ?

What is NULL in mysql ? -

The NULL value is special; because it means “no value”. It is basically a condition, to check whether particular field value is null or not.

If we are not defining the column NOTNULL than MYSQL make it NULL by-default. But We shouldn’t define fields as NULL for any field due to some following reasons -

• If you make any field NULL, it requires more storage space and requires special processing inside MYSQL.

• A nullable column requires extra byte per entry on the time of indexing a column.

• Its harder for MYSQL to optimize queries that refer to nullable column because nullable columns make indexes   and comparisions to value becomes more complicated inside MYSQL.

So, We should define fields as NOT NULL whenever We can.

For Eg. We need to make a table of Oscar awarded singers with columns: firstname , lastname, city, birthdate, death:
All singers will have firstname, lastname, city and birthdate but there can be lot of singers who has been expired.
So, we can put only deathdate column NULL.

CREATE TABLE singers
(
lastname VARCHAR(15) NOT NULL,
firstname VARCHAR(15) NOT NULL,
city VARCHAR(20) NOT NULL,
birthdate  DATE NOT NULL,
deathdate DATE NULL
)

So never forget to define NOTNULL  to any field on which any value must exist….

Hope it will help for your MYSQL optimization….

form_for :

we used form_for for a specific model i.e while we need to
create a new row in database. so, form_for perform the standard http post method and posses active record objects.

Below is the example for using form_for form helper:
view sourceprint?

<% form_for @client do |f| %>

First name: <%= f.text_field :firstname %>

Last name : <%= f.text_field :lastname %>

Email : <%= f.text_field :email %>

Address : <%= f.text_area :address %>

<% end %>

here we are using f object of model class “Client” to create form input fields

form_tag :

form_tag just creates an form as an normal form. form_for
will perform the standard http post without any model
backed and has normal fields. this is used mainly when
specific things need to be submitted via form

here is the example for using form_tag in ruby on rails:
view sourceprint?

<% form_tag ‘/posts’ do -%>

<%= text_field_tag “post”, “firstname” %>

<% end -%>