Sql updating table based another table
It will refer to the state corresponding to the time you executed COMMIT.
This means if you have already used COMMIT 10 times, ROLLBACK will have an effect on the last execution you have performed.
Please note that it will be very hard to practice these statements unless we switch off the following feature of Workbench.
We can expand the Edit tab from the Main Menu and opt for “Preferences”.
In some databases, such as Postgre SQL, when a FROM clause is present, what essentially happens is that the target table is joined to the tables mentioned in the fromlist, and each output row of the join represents an update operation for the target table.
When using FROM, one should ensure that the join produces at most one output row for each row to be modified.
Along with 16 years of hands on experience he holds a Masters of Science degree and a number of database certifications.
In recent times I have seen a developer writing a cursor to update a table. We want to update the value from Table2 to Table1 for the rows where Col1 is 21 and 31.
When asked the reason was he had no idea how to use multiple tables with the help of the JOIN clause in the UPDATE statement. Additionally, we want to update the values of Col2 and Col3 only.
We are going to update column DESCRIPTION and PICTURE in table Categories_Test by using data in table Categories, based on data in the common column CATEGORY_ID. Update data in a column in table A based on a common column in table B. Update data in two columns in table A based on a common column in table B. Conditionally update data in table A based on a common column in table B. No portion may be reproduced without my written permission.
The update query below shows that the PICTURE column is updated by looking up the same ID value in CATEGORY_ID column in table Categories_Test and Categories. If you need to update multiple columns simultaneously, use comma to separate each column after the SET keyword. Here we only want to update PICTURE column in Categories_Test table where the data in Category_Name column is Seafood in table Categories. Software and hardware names mentioned on this site are registered trademarks of their respective companies.