Microsoft Sql Server

Introduction

• Microsoft SQL Server is a relational database management system which stores data in tabular format that is columns and rows wise.

• Sql server major components 1. Database Engine2. Sql Server Integration Services (SSIS)3. Sql Server Analyses Services (SSAS)4. Sql Server Reporting Services (SSRS)

Database Engine

• Its task is to provide cores functionalities that is storing and retrieving the data in very efficient manner.

1. Creating database objects like table, view, stored procedure etc.

2. Retrieving, updating, inserting, deleting or merging data from different database objects.

3. Sending email notification when data is modified. 4. Perform some database scheduled jobs etc.

Integration Services(SSIS)

• It can load the 1 TB data in 30 minutes.

• Its task is to extract the data from different sources likes databases, raw files, XML etc, perform some operations (likes data cleaning, sending emails etc) and load the data into different destinations.

• Download the data from FTP severs, correct the spelling, verb forms etc of data and save in the XML file.

Analyses Services(SSAS)

• Its task is to create multi dimensional data structure of an OLAP system, analyze and aggregate the data. Also it implements various data mining models.

1. Get the detail information of sold car over last 10 years for that family which has three children.

2. Forecasting sales in coming year etc.

Reporting Services(SSIS)

• Generate a report by getting data from different tables in PDF format.

• Generate a report to display total sales in different location of a country in map view.

• Generate a pie chart to display purchase volume.

SELECT statement

1. FROM2. ON3. JOIN4. WHERE5. GROUP BY6. WITH CUBE or WITH ROLLUP7. HAVING8. SELECT9. DISTINCT10. ORDER BY11. TOP

FROM clause• [Linked_Server].[Database_Name].[Schema_Name].[Table_Name]

WHERE Clause

• This clause filters the records from data source.

• Wrongly written filter predicates(conditions) can badly decreases the query performance.

Why order doesn't matter?

• Comparison with string is costlier than integer comparison.

• LIKE is itself a costly operator.

• Also if first filter condition will return less result set then other filter condition has to perform less number of comparisons.

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