MYSQL

1.What is the diff between primary key and foriegn key?


PRIMARY KEY: A tabLe can aontain only one PRIMARY KEY. It
Doesn't allow null values, it is used  as Foreign Key In
Another Table(like Reference Key).

UNIQUE KEY: A Table may Contain  one or more UNIQUE 
constraints. Its aloow only one null value . Use this key We
maintain unique vales in the table.

FOREIGN KEY: A key used in one table  to represent the value
of a primary key in a related table. While primary keys must
contain unique values, foreign keys may have duplicates. For
instance, if we use student ID as the primary key in a
Students table (each student has a unique ID), we could use
student ID as a foreign key in a Courses table: as each
student may do more than one course, the student ID field in
the Courses table (often shortened to Courses.student ID)
will hold duplicate values.
 
 
 
 
 
 
 
 

SQL DML and DDL

SQL can be divided into two parts: The Data Manipulation Language (DML) and the Data Definition Language (DDL).
The query and update commands form the DML part of SQL:
  • SELECT - extracts data from a database
  • UPDATE - updates data in a database
  • DELETE - deletes data from a database
  • INSERT INTO - inserts new data into a database
The DDL part of SQL permits database tables to be created or deleted. It also defines indexes (keys), specifies links between tables, and imposes constraints between tables. The most important DDL statements in SQL are:
  • CREATE DATABASE - creates a new database
  • ALTER DATABASE - modifies a database
  • CREATE TABLE - creates a new table
  • ALTER TABLE - modifies a table
  • DROP TABLE - deletes a table
  • CREATE INDEX - creates an index (search key)
  • DROP INDEX - deletes an index 







The DISTINCT keyword can be used to return only distinct (different) values.

SELECT DISTINCT column_name(s) FROM table_name



The AND & OR operators are used to filter records based on more than one condition.


 Note : following concepts are important concepts in mysql
and their referencelinks, of courese i have read this alredy
 
 
1.Fetch

ref link: http://www.tutorialarena.com/mysql/php-mysql-fetch-array.php

2.Aggregate Functions  and Group By

ref link: http://www.tizag.com/mysqlTutorial/mysqlgroupby.php

3.Joins

ref link: http://www.tutorialspoint.com/mysql/mysql-using-joins.htm

4.As alias :

ref link: http://www.w3schools.com/sql/sql_alias.asp

5.Like
ref link: http://www.mysqltutorial.org/sql-like-mysql.aspx

6.Date and time: 


Ref links: http://www.tutorialspoint.com/mysql/mysql-date-time-functions.htm
           http://www.plus2net.com/sql_tutorial/date.php

7.Mysql functions


8. Adding one or more tables to a query


9.Table prefix's for columns


10.write a query in another query



Mysql Ref links for Knowledge
http://databases.aspfaq.com/database/how-do-i-use-a-select-list-alias-in-the-where-or-group-by-clause.html


2.http://beginner-sql-tutorial.com/sql-query-tuning.htm



3.http://www.tizag.com/mysqlTutorial/index.php


4.http://www.tutorialarena.com/mysql/mysql-group-by.php


5.http://www.tutorialspoint.com/mysql/mysql-like-clause.htm


6.http://www.mysqltutorial.org/basic-mysql-tutorial.aspx 
 
 
8.What is the difference between  loadObjectList and  loadResult?
   1.loadObjectList returns the result in object format means while we print the  output   using this 


<?php echo  $lists->title ; ?>  

 2.loadResult returns the result in array format  while we print the  output   using this

<?php echo $list[title]; ?>  


   we need to print the key value , here title is key value of array






9.Full text serach using match function used fro searching the word /character from more than one column of table?


plz go through this
http://devzone.zend.com/article/1304
 
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