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This article is about how to get the first piece of data recorded in SQL. The editor thinks it is very practical, so I share it with you. I hope you can get something after reading this article. Let's take a look at it.

Using the Northwind database

First query the Employees table

There are only five cities in the city column.

Use ROW_NUMBER () OVER (PARTITION BY COL1 ORDER BY COL2) to group notes first: group according to COL1, sort according to COL2 within the group, and the value calculated by this function represents the sorted sequence number within each group (continuous and unique within the group).

The sql statement is:

Select EmployeeID,LastName,FirstName,Title,TitleOfCourtesy,City,ROW_NUMBER () over (partition by City order by EmployeeID) as new_index from Employees

You can see that it is grouped by City and sorted by EmployeeID.

The first record in the select outgoing packet

Execute the statement:

Select * from (select EmployeeID,LastName,FirstName,Title,TitleOfCourtesy,City,ROW_NUMBER () over (partition by City order by EmployeeID) as new_index from Employees) a where a.new_index=1

The above is the method of how to get the first piece of data recorded in SQL. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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