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Vivek's SQL Notes

Vivek johari is currently a Analyst and have more that 5.5 yeras of experience in database. He has Master degree in Computer and also he is Microsoft certified Sql DBA (MCTS)& Microsoft certified SQl BI professional(MCTS). He is also Oracle certified profession(OCP)DBA in ORACLE 10g and ORACLE 9i.He has the experience of working in PL/SQL, T-SQL and SSIS/SSRS. His work basically involved designing and optimization of the Database.He has also published many database articles on his blog Technologies with Vivek Johari.

Archives: January 2010

Interview Questions on Sql Server -Part 3


1. What are the Sql Joins?
Sql Joins are the way to get data from many tables based on some logical conditions. The different  types of Joins in Sql Server are

1) Inner join or Equi join
2) Self Join (it can be considered as the part of Inner join)

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0 comments, 974 reads

Posted in Vivek's SQL Notes on 31 January 2010

Interview Questions On Sql Server -Part 2

1. What is the difference between the Union and Union All?

1) Union is used to select distinct data from the tables but Union All allows duplicate rows to be selected from the tables.

2) The second difference between Union and Union All can be given on the basic of…

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0 comments, 855 reads

Posted in Vivek's SQL Notes on 31 January 2010

Interview Questions on sql server -Part-1


1. What is the Normalization?
Normalization:-Normalization can be defined as the process of organization the data to reduce the redundant table data to the minimum. This process is carried out by dividing the database into two or more than two tables and defining relationship between them so that deletion,…

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0 comments, 872 reads

Posted in Vivek's SQL Notes on 31 January 2010

Group by.....Having Clause

Group By:- Group By clauses is used to groups rows based on the distinct values of the specified columns.

The syntax of the Group by clause is:-
  Select column1, column2, column3, aggregate_function(expression ) 
           From TableName Where (condition) 
           Group By Column1, column2, column3

For…

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0 comments, 1,341 reads

Posted in Vivek's SQL Notes on 31 January 2010

Difference Between Having and Where Clause in Sql Server


Both Having Clause and Where clause is used to filter the data coming from the Select statement, but still there are some differences between them. These difference are given below:-

To show the difference between the Where Clause and the Having clause we will going to use the table EmployeeDeptInfo…

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0 comments, 3,726 reads

Posted in Vivek's SQL Notes on 31 January 2010

How to find duplicate values in a table

Sometimes duplicate values in tables can create a major problem when we do not make a primary key or a unique key on a table. In these cases we need to find out the duplicate records and need to delete them. We can use the Having Clause to find out…

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0 comments, 1,014 reads

Posted in Vivek's SQL Notes on 31 January 2010

Sql Server View


Views:- View can be described as virtual table which derived its data from one or more than one table columns.It is stored in the database. It is used to implements the security mechanism in the Sql Server. For example, suppose there is table called Employeeinfo whose structure is given below:-

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0 comments, 762 reads

Posted in Vivek's SQL Notes on 31 January 2010

Second Normal Form (2NF)


Second Normal Form (2NF) :-A table is said to be in its Second Normal Form if it satisfied the following conditions:-
1) It satisfies the condition for the First Normal Form (1NF),
2) It do not includes any partial dependencies where a column is dependent only a part of…

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0 comments, 456 reads

Posted in Vivek's SQL Notes on 26 January 2010

Third Normal Form (3NF)

Third Normal Form (3NF) :- A table is said to be in the Third Normal form (3NF) if it satisfy the following conditions:-
1) It should be in the 2NF
2) It should not contain any transitive dependency which means that any non key column of the table should not…

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0 comments, 486 reads

Posted in Vivek's SQL Notes on 26 January 2010

First Normal form (INF)

First Normal Form (INF):- A table is said to be in a First Normal Form (1NF)if it satisfy the following conditions:-
1)If the columns of the table only contain atomic values (Single, indivisible).
2)Primary key is defined for the table
3)All the columns of the table are defined on the…

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0 comments, 352 reads

Posted in Vivek's SQL Notes on 26 January 2010

Database Normalization


Normalization :- Normalization can be defined as the process of organization the data to reduce the redundant table data to the minimum. This process is carried out by dividing the database into two or more than two tables and defining relationship between them so that deletion, updation and insertion can…

Read more

0 comments, 1,344 reads

Posted in Vivek's SQL Notes on 26 January 2010

Indexes in Sql server


Indexes-Indexing  is way to sort and search records in the table. It will improve the speed of locating and retrieval of records from the table.It can be compared with the index which we use in the book to search a particular record.


In Sql Server there are two types…

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0 comments, 295 reads

Posted in Vivek's SQL Notes on 3 January 2010

Difference between Clustered Index and Non clustered Index

Indexes-Indexing  is way to sort and search records in the table. It will improve the speed of locating and retrieval of records from the table.It can be compared with the index which we use in the book to search a particular record.

In Sql Server there are two types…

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0 comments, 410 reads

Posted in Vivek's SQL Notes on 3 January 2010

Sql Joins- Inner Joins, Self Joins, Outer Joins, Cross Joins


I generally feel that people are afraid of Joins in SQL Server. But if they know what the different types of Joins in SQL Server are and how they can be best used then they really enjoy using them. By using the joins we can get data from many tables…

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0 comments, 2,232 reads

Posted in Vivek's SQL Notes on 2 January 2010