How to UPDATE from SELECT in SQL Server 5

How to UPDATE from SELECT in SQL Server

How to write a query to UPDATE columns in a table by using the SELECT statement with an example? This Update from Select in SQL server is one of the Frequently Asked Questions. For this example, We are going to use the below shown data.

Employee Data 1

The below table will show the data present in the Employee Duplicate table. Our task is to update the columns (firstname, lastname, and Yearly Income) in this table with the above-specified table.

Duplicate Employee records 2

How to UPDATE from SELECT in SQL Server Example?

In this example, we will show you how to update from the select statement using Subquery.

UPDATE [EmployeeDuplicates]
   SET [YearlyIncome] = ( SELECT [YearlyIncome] 
			  FROM [Employee]
			  WHERE [Employee].EmpID = [EmployeeDuplicates].EmpID)
 
GO
Messages
--------
(14 row(s) affected)

Now let me show you the SQL Server Updated table

How to UPDATE from SELECT in SQL Server 4

How to UPDATE from SELECT Example 2

The above-specified example might be an excellent option to update a single column. In this update select example, let us see how we can make an UPDATE statement with JOIN in SQL Server.

UPDATE [EmpDup]
   SET [EmpDup].[FirstName] = [Emp].[FirstName],
	   [EmpDup].[LastName] = [Emp].[LastName],
	   [EmpDup].[YearlyIncome] = [Emp].[YearlyIncome]
FROM [EmployeeDuplicates] AS [EmpDup]
INNER JOIN [Employee] AS [Emp] 
   ON [EmpDup].EmpID = [Emp].EmpID 
WHERE [EmpDup].EmpID = [Emp].EmpID 
GO
How to UPDATE from SELECT in SQL Server 5

Now let me show you the Updated table

View Employee Records 6

UPDATE SELECT Example 3

In this example, we show you how to update the table columns using the Select statement. Here, we are using the Subquery at FROM statement.

UPDATE [EmployeeDuplicates]
   SET [FirstName] = [Emp].[FirstName],
	   [LastName] = [Emp].[LastName],
	   [YearlyIncome] = [Emp].[YearlyIncome]
FROM (SELECT EmpID,
	     [FirstName], 
	     [LastName],
	     [YearlyIncome] 
       FROM [Employee]
     ) [Emp] 
WHERE [EmployeeDuplicates].EmpID = [Emp].EmpID 
GO
How to UPDATE from SELECT in SQL Server 9

Now let me show you the Updated table

table records 10

How to UPDATE from SELECT Example 4

In this example, we will show you, How to update the table columns from the Select statement using the MERGE Statement in Sql Server.

MERGE INTO [EmployeeDuplicates] AS [EmpDup]
   USING (
           SELECT EmpID,
		  [FirstName], 
		  [LastName],
		  [YearlyIncome] 
           FROM [Employee] 
         ) [Emp]
   ON [EmpDup].EmpID = [Emp].EmpID
WHEN MATCHED THEN
   UPDATE 
  	SET [EmpDup].[FirstName] = [Emp].[FirstName],
	    [EmpDup].[LastName] = [Emp].[LastName],
	    [EmpDup].[YearlyIncome] = [Emp].[YearlyIncome];

Run the above merge update from the select query

Messages
--------
(14 row(s) affected)

Now let me show you the Updated table using this update from the select statement.

View records 8