However, users may assign null values to columns for which they do not want to assign a value.
In addition, the PARTITION clause must be included in the DML.
clause; columns not explicitly modified retain their previous values.
If the item already exists, instead update the stock count of the existing item.
To do this without failing the entire transaction, use savepoints: BEGIN; -- other operations SAVEPOINT sp1; INSERT INTO wines VALUES('Chateau Lafite 2003', '24'); -- Assume the above fails because of a unique key violation, -- so now we issue these commands: ROLLBACK TO sp1; UPDATE wines SET stock = stock 24 WHERE winename = 'Chateau Lafite 2003'; -- continue with other operations, and eventually COMMIT; If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.
The UPDATE and DELETE statements enable users to modify and delete values already written to Hive.
The MERGE statement streamlines UPDATEs, DELETEs, and change data capture operations by drawing on coexisting tables.
Run the following commands to set the CATEGORY table data back to the original values: update category set catdesc='Broadway Musical' where category.catid in (select category.catid from category join event on category.catid = event.catid join venue on venue.venueid = event.venueid join sales on sales.eventid = event.eventid where venuecity='New York City' and catname='Musicals');select * from category order by 1; catid | catgroup | catname | catdesc ------- ---------- ----------- -------------------------------------------- 1 | Sports | MLB | Major League Baseball 2 | Sports | NHL | National Hockey League 3 | Sports | NFL | National Football League 4 | Sports | NBA | National Basketball Association 5 | Sports | MLS | Major League Soccer 6 | Shows | Musicals | Broadway Musical 7 | Shows | Plays | All non-musical theatre 8 | Shows | Opera | All opera and light opera 9 | Concerts | Pop | All rock and pop music concerts 10 | Concerts | Jazz | All jazz singers and bands 11 | Concerts | Classical | All symphony, concerto, and choir concerts (11 rows)update category set catid=100 from event where event.catid=category.catid; select * from category order by 1; catid | catgroup | catname | catdesc ------- ---------- ----------- -------------------------------------------- 1 | Sports | MLB | Major League Baseball 2 | Sports | NHL | National Hockey League 3 | Sports | NFL | National Football League 4 | Sports | NBA | National Basketball Association 5 | Sports | MLS | Major League Soccer 10 | Concerts | Jazz | All jazz singers and bands 11 | Concerts | Classical | All symphony, concerto, and choir concerts 100 | Shows | Opera | All opera and light opera 100 | Shows | Musicals | Musical theatre 100 | Concerts | Pop | All rock and pop music concerts 100 | Shows | Plays | All non-musical theatre (11 rows) Note that the EVENT table is listed in the FROM clause and the join condition to the target table is defined in the WHERE clause. These four rows are the rows whose CATID values were originally 6, 7, 8, and 9; only those four categories are represented in the EVENT table: Update the original 11 rows in the CATEGORY table by extending the previous example and adding another condition to the WHERE clause.
Because of the restriction on the CATGROUP column, only one row qualifies for the update (although four rows qualify for the join).
If you want to review the complete syntax of the UPDATE statement then please refer to Books Online.
To properly show you how to use the UPDATE statement I will need to create a few tables to hold some sample data. Below is the code to create my Toy table: In order to show you how to UPDATE a table from data in another table I need to build a second sample data table that I will call New Toy Price.
update category set catid=100 from event where event.catid=category.catid and catgroup='Concerts'; select * from category where catid=100; catid | catgroup | catname | catdesc ------- ---------- --------- --------------------------------- 100 | Concerts | Pop | All rock and pop music concerts (1 row) The advantage to this approach is that the join criteria are clearly separated from any other criteria that qualify rows for the update.
Note the use of the alias CAT for the CATEGORY table in the FROM clause.
You find that an error in a system has been incorrectly naming men (M) as women (W) and vice versa in the database. Without using any temp tables, write one update query to resolve this.