![]() 9 records of pasta dishes from the United States and the Philippines.Īgain, if you run the code above twice, the second run won’t have records inserted. There are 9 records inserted from this statement – see Figure 2 below: Figure 2. WHERE a.PastaDishName NOT IN (SELECT PastaDishName FROM PastaDishes) INNER JOIN Origin b ON a.Origin = b.Origin Here goes: - Insert pasta dishes from the United States (22) and the Philippines (15) using NOT IN We picked pasta dishes from the United States and the Philippines. Since we are only at the second point of this post, we won’t insert everything. Next, we need to populate the PastaDishes table from the NonItalianPastaDishes table. It filters out records that already exist in the target table. It happens because of the WHERE clause with the NOT IN operator. The second time it runs won’t have records inserted. Since ItalianPastaDishes contains raw data, we need to join the Origin text instead of the OriginID. WHERE a.DishName NOT IN (SELECT PastaDishName FROM PastaDishes) INNER JOIN Origin b ON a.ItalianRegion + ', ' + 'Italy' = b.Origin For that, we need first to insert records from the ItalianPastaDishes table. So, do not run these statements more than once. It is good when you’re sure that the target table doesn’t have the values you want to insert. However, it does not guarantee that duplicates do not exist in the target table. Using DISTINCT will make unique records out of the SELECT statement. SELECT DISTINCT ItalianRegion + ', ' + 'Italy' SELECT DISTINCT origin FROM NonItalianPastaDishes Here’s the correct code: - The correct way to INSERT To prevent it, add the DISTINCT keyword to make the result set unique. That’s the reason for the first SQL duplicate error. There are 5 entries for the United States. To start the SQL check for duplicates that existed before, I ran the SELECT part of the INSERT INTO SELECT statement: Figure 1. There’s a problem when you try to select duplicate rows in SQL. The duplicate key value is (Lombardy, Italy). The duplicate key value is (United States).Ĭannot insert duplicate key row in object 'dbo.Origin' with unique index 'UIX_Origin'. This will trigger the following duplicate errors: Msg 2601, Level 14, State 1, Line 2Ĭannot insert a duplicate key row in object 'dbo.Origin' with unique index 'UIX_Origin'. But first, let’s use the wrong method: - This is wrong and will trigger duplicate key errors To explore the case, we’ll populate the Origin table. The first option for how to identify SQL records in SQL is to use DISTINCT in your SELECT. Therefore, removing the unique constraints is not one of the five ways to handle or delete duplicate records in SQL. And what if we have a user interface with a dropdown list for picking the origin of the pasta dish? Will the duplicates make your users happy? With unique constraints gone, it’s easy to make a mistake and insert the data twice or more. The easiest way to handle duplicates is to remove unique constraints, right? 5 Easy Ways to Handle Duplicates Using SQL INSERT INTO SELECT Restrictions will make this journey a bit harder but exciting. It will prevent us from inserting duplicate records later. Note: There are unique indexes created on two tables. ![]() WITH CHECK ADD CONSTRAINT FOREIGN KEY()ĪLTER TABLE. ADD CONSTRAINT DEFAULT (getdate()) FOR ĬREATE UNIQUE NONCLUSTERED INDEX ON. (ĬONSTRAINT PRIMARY KEY CLUSTEREDĪLTER TABLE. Let’s define the two output tables with the command SQL Server ALTER TABLE. I named the tables dbo.ItalianPastaDishes and dbo.NonItalianPastaDishes. You can either use SQL Server Management Studio or dbForge Studio for SQL Server to import 2 sheets into the Excel file.Ĭreate a blank database before importing the data. Using INSERT INTO SELECT will help us do this task, Import the Data in SQL Server It’s raw because we are going to make 2 relational tables out of it. Now we have the data – you can download it from here. Cleaned it up a bit and copied data to Excel. Then I specified the 2-table data from the page. I found a good list of pasta dishes in Wikipedia that we can use and extracted in Power BI using a web data source. I kind of thinking about pasta this time. Prepare Test Data for SQL INSERT INTO SELECT Code Samples
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |