Difference Between Union and Union all
Union and Union all both the command is used concatenate the two different SQL result. Then what will be the difference let see… Union The union is the command used to link the two SQL Result. But it removes all the Duplicate data. For example, Here I am taking two tables from AdventureWorks2008 Database and one is currency Table and another one is Currency rate table. In that table, I Taking Currency code and ToCurrencyCode Data. Select * from sales.Currency Select * from sales.CurrencyRate Example For Union :- Select CurrencyCode from Sales.Currency Union Select FromCurrencyCode from Sales.CurrencyRate You can see it will all the duplicate in the table. In Below picture only 105 rows are affected. Example For Union Union All Union All doing the same job, But unlike Union it shows all the rows of the Data’s in two tables. It will not remove any duplicate rows in the table. Example for Union all : Select CurrencyCode ,Name from Sales.Currency ...
