What is difference between data mart and data warehouse?
Data Warehouse is a big central repository of historical data. This data is assembled from different departments and units of the company. Data Mart can be considered as a subset of data warehouse or simply a data repository which is generally focused on a single functional area. They both primarily vary in their scope and usage area.
What is difference between simple view and complex view?
Views in SQL is nothing but the logical table created from one or more tables.We can use the views to fetch the columns from one or more different tables at a time.In real life specifically views are used in Reporting purpose.To create a report we need data from different tables and need to show it on a single dashboard so we are using the views to fetch the data from different tables.View can contain all rows from the table or selected rows from the table.
SQL Query Performance Improvement
SQL statements are basically used for manipulation of data or data retrieval.When we consider the large software,industrial software it has very high volume of data.So there is huge need of tuning the query which will improves the performance of data and application.There are lot of factors we need to consider in Performance tuning like the Server hardware,Speed of Server,Database using,Volume of data e.t.c.In this article i am giving you the basic idea of SQL Performance Tuning Techniques.We will get same result using multiple type of queries.But by considering the cost and execution of the query we will able to tune our sql and improve the performance.