Learn SQL Commands

Learn T-SQL Commands with Samples

	Database


	Table


	View


	Stored Procedure


	Data Filtering


	Data Grouping


	Joins


	Trigger


	Cursor


	Operators


	Constraints


	Functions


	Conditional Processing


	Looping


	Error Handling


	v.IMP Queries


	XML


	Query Performance


		Use Joins instead of Subqueries


		Use Parameterized Queries


		Use BETWEEN instead of IN


		Use LIKE instead of SUBSTRING


		Use DISTINCT instead of GROUP BY


		Index


	Queries


	Normalization


	Create

Use DISTINCT instead of GROUP BY

 ----  Low Performance by using GROUP BY 
      SELECT    Country
      FROM      EMP
      WHERE     ID      BETWEEN 1 AND 5
      GROUP BY  Country


       ----  High Performance by using DISTINCT 
      SELECT  DISTINCT Country
      FROM    EMP
      WHERE   ID       BETWEEN 1 AND 5

 ----  both Queries will give the same output but Performance is different, if the data is tooooo big 
          
          Output
          
          Country   
          
          
          France
          
          
          India
          
          
          USA