Skip to main content

Some Of Mysql Commands..

########## MYSQL COMMANDS #######################
  mysql -u root -p
  use databasename;
1)display all tables in database.
  show tables;
2)display all the fields from single table.
  desc users;
3)Display all recorde in single table
  select * from users;
4)Count the recorde in single table
  select count(*) from users;
5)Display Distinct 
  select distinct name from users;
  select * from users where first_name = "chinna";
  select * from users where first_name = "chinna" and last_name = "ram";
  select * from users where first_name = "chinna" or last_name = "ram";
  delete from users;
  delete from users where first_name = "chinna";
  update from users  set first_name "ramu" where user_id = 67;
  select first_name from users order by first_name asc;
  select first_name from users order by first_name desc;
  explain select * from users;

Comments

Popular posts from this blog

Error malloc(): memory corruption nginx with passenger?

Error malloc(): memory corruption nginx with passenger Passenger issue resolving steps :  sudo gem uninstall passenger(uninstall all passenger) sudo gem install passenger sudo passenger-install-nginx-module --auto --auto-download --prefix=/opt/nginx --extra-configure-flags=none Update nginx config file with new passenger version and restart the nginx

Rails Migration Difference between Text and String

Rails Migration Difference between Text and String ? While working with Rails Migration Difference between Text and String is important to be known to every developer. Columns and their data types are finalized while deciding Table structure. This tutorial will help understand difference between String and Text column type and illustrate how to write Rails Migration implementing the same. You might want to read about database.yml files for specifying database configuration for Rails Application. 1. Concepts When String or Text data type is required?     Whenever you require your column to store information which is lengthy in size (Many characters), you need to consider String or Text data type for the column.     Both of them let you store Many(How Many - will see later) characters Difference between String and Text Considering MySQL database Feature     String     Text Length     1 to 255     ...

RSPEC TESTCASES FOR MODEL VALIDATIONS IN RAILS

describe User do    before(:each) do     @user_new = { :name => "chinna",:email => "chinna@yopmail.com",:password => "chinnaram",:password_confirmation => "chinnaram"}    end it "should create a new user details" do      @user_attr = User.create!(@user_new) end ##validations in your model ########### User.rb(your model your mention like that....) validates :name,:email,:presence => true validates :name,:uniqueness => true validates_attachment_content_type :image, :content_type => ['image/jpeg', 'image/png','image/pjpeg','image/x-png','image/gif'] ###validation for name presence it "should require a name" do      user = User.new(@user_attr.merge(:name => ""))      user.should_not be_valid   end #validation for email presence  it "should require a email" do      user = User.new(@user_attr.merge(:email => ""))      user...