![]() ![]() See Identifier Qualifiers for syntax details. This permits writing UNIONs which involve multiple databases. Note that currently this is not the case for recursive CTEs - see MDEV-12325. If they don't, the type and length of the columns in the result take into account the values returned by all of the SELECTs, so there is no need for explicit casting. (For example, the first column selected by the first statement should have the same type as the first column selected by the other statements.) Selected columns listed in corresponding positions of each SELECT statement should have the same data type. The column names from the first SELECT statement are used as the column names for the results returned. And to combine the results, we are using the UNION ALL operator between the SELECT statements.UNION is used to combine the results from multiple SELECT statements into a single result set. Moreover, we are also using a WHERE clause with each SELECT statement to fetch records where the country is Canada. And in the definition, we are using 2 SELECT statements to fetch the name, city, and country columns from respective tables. In the above example, we have created a view with the name CityView_CA. SELECT Name, City, Country FROM dbo.Customers_2 SELECT Name, City, Country FROM dbo.Customers_1 But, with the help of the UNION ALL operator, we can even combine duplicate entries of multiple SELECT statements within a single view. Generally, a simple view in SQL Server includes the use of a single select statement. Similar to UNION operator in a SQL Server VIEW, using UNION ALL is also quite simple. Now that we have a clear idea of how to use the UNION operator in a SQL Server View, let’s understand how to use the UNION ALL operator in a view. Read How to view table in SQL Server How to use union all in view SQL Server So, the view will return the distinct city names from both the tables that come under the United States. Moreover, we are also using a WHERE clause with each SELECT statement to fetch records where the country is the United States. And in the definition, we are using 2 SELECT statements to fetch the city and country columns from respective tables. In the above example, we have created a view with the name US_CityView. SELECT City, Country FROM dbo.Customers_2 SELECT City, Country FROM dbo.Customers_1 And again for this example, we will use the same tables illustrated in the previous section. Let’s understand the whole implementation using an example. But, with the help of the UNION operator, we can combine the results of multiple SELECT statements within a single view. So, using a UNION operator in a SQL Server VIEW is quite simple. Now that we have a clear idea about the use of the UNION operator, let’s understand how to use it in a view in SQL Server. Read SQL Server view order by How to use union in view SQL Server Now, from the above outputs, we can easily understand the difference between UNION and UNION ALL operators. Let’s understand the syntax of using the UNION and UNION ALL operator in SQL Server. A UNION operator in SQL Server does not include duplicate entries, while the UNION ALL operator includes duplicates in the result. Now, there is a slight difference between a UNION and a UNION ALL operator in SQL Server. As the name specifies, the main aim of the UNION operator is to perform the UNION operation. ![]() In SQL Server, the UNION operator is used to perform a set operation of combining the results of multiple SELECT queries. Read Create a table from view in SQL Server Union & Union All in SQL Server Moreover, we can also specify any sort of condition with the SELECT statement. After this, we can use the SELECT statement to fetch some columns from a table.Now, after CREATE VIEW keyword, we have to specify the name of the view instead of view_name.In the syntax, we are using the CREATE VIEW statement to create a simple user-defined view in SQL Server.In this section, we will only cover the syntax of creating a view in SQL Server. For more information, refer to “ View in SQL Server“. A view includes a set of SQL queries for retrieving data from the database. In SQL Server, a VIEW is just like a virtual table that holds data from one or more than one table. How to use union all in view SQL Server. ![]()
0 Comments
Leave a Reply. |