Can I update/select from a table in one query? - mysql

Question

I need to select data when a page is viewed and update the 'views' column is there a way to do this in one query, or do I have to use to distinct queries?

Answer 1

If you do not want/need to use a transaction, you could create a stored procedure that first updates the view count and then selects the values and return them to the user.

Answer 2

You would have to do this in two statements in one transaction
Begin Tran
Update Pages Set Views = Views + 1 Where ID = #ID
Select Columns From Pages Where ID = #ID
Commit Tran

Answer 3

It would help if you listed the RDBMS you are using
SQL Server has the OUTPUT statement
Example
USE AdventureWorks;
GO
DECLARE #MyTestVar table (
OldScrapReasonID int NOT NULL,
NewScrapReasonID int NOT NULL,
WorkOrderID int NOT NULL,
ProductID int NOT NULL,
ProductName nvarchar(50)NOT NULL);
UPDATE Production.WorkOrder
SET ScrapReasonID = 4
OUTPUT DELETED.ScrapReasonID,
INSERTED.ScrapReasonID,
INSERTED.WorkOrderID,
INSERTED.ProductID,
p.Name
INTO #MyTestVar
FROM Production.WorkOrder AS wo
INNER JOIN Production.Product AS p
ON wo.ProductID = p.ProductID
AND wo.ScrapReasonID= 16
AND p.ProductID = 733;
SELECT OldScrapReasonID, NewScrapReasonID, WorkOrderID,
ProductID, ProductName
FROM #MyTestVar;
GO

Answer 4

PostgreSQL's UPDATE statement has the RETURNING clause that will return a result set like a SELECT statement:
UPDATE mytable
SET views = 5
WHERE id = 16
RETURNING id, views, othercolumn;
I'm pretty sure this is not standard though. I don't know if any other databases implement it.
Edit: I just noticed that your question has the "MySQL" tag. Maybe you should mention it in the question itself. It's a good generic database question though - I would like to see how to do it in other databases.

Answer 5

I used this trick with Java and SQL Server will also let you send two commands in a single PreparedStatement.
update tablex set y=z where a=b \r\n select a,b,y,z from tablex
This will need to be in a read committed transaction to work like you think it should though.