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Updating multiple table

My first attempt, which was incorrect, was this: The problem with this update statement was that I realized it would update all 5 records instead of just the 2 records accounting wanted to update; this would result in 103 and 104 being updated to the updated amounts, but all other amounts wiped out to null value.

To remedy that, we could throw in a where clause to the update statement, as below: -- Better example, but still inefficient update master_table m set m.invoice_amount=( select a.updated_invoice_amount from data_from_accounting a where m.job_number=a.job_number ) where m.job_number in( select a2.job_number from data_from_accounting a2 where m.job_number=a2.job_number ); This would correctly update the records I wanted to update while leaving the others alone, but this query is a little inefficient as it needs to go through the data from accounting twice.

In order for the "best practice" update statement to work, they must be either primary keys or unique indexes, otherwise the query will fail with the error message "ORA-01779: Cannot modify a column which maps to a non key-preserved table".

As an aside, to create primary key or unique indexes, follow the examples below.

If you get an error, either the view is not logically updatable, or the query processor can't tell that it is.

My SQL UPDATE using NULL My SQL UPDATE command can be used to update a column value to NULL by setting column_name = NULL, where column_name is the name of the column to be updated.Note the use of the alias CAT for the CATEGORY table in the FROM clause.The previous example showed an inner join specified in the FROM clause of an UPDATE statement. If you omit the WHERE clause, all records in the table will be updated! The WHERE clause specifies which record(s) that should be updated.After each exercise, we provide the solution so you can check your answer. My SQL UPDATE with WHERE My SQL UPDATE command can be used with WHERE clause to filter (against certain conditions) which rows will be updated.Thus, we need an update statement that is efficient.Because Oracle does not allow multiple tables within the same update statement, I know at least one subquery will be needed.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 | Musical theatre 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)select * from category where catid between 6 and 8; catid | catgroup | catname | catdesc ------- ---------- ----------- -------------------------------------------- 6 | Theatre | Musicals | Musical theatre 7 | Theatre | Plays | All non-musical theatre 8 | Theatre | Opera | All opera and light opera (3 rows)select * from category where catname='Shows'; catid | catgroup | catname | catdesc ------- ---------- ----------- -------------------------------------------- 6 | Theatre | Shows | 7 | Theatre | Shows | 8 | Theatre | Shows | (3 rows)In this case, the CATDESC column was set to null because no default value was defined when the table was created.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.

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  1. Days ago. The ORDER BY clause is used to update the order that is already specified. The LIMIT clause specifies a limit on the number of rows that can be updated. For multiple tables, UPDATE updates row in each table named in table_references that satisfy the conditions. In this case, ORDER BY and LIMIT cannot.

  2. UPDATE Syntax. UPDATE table_name. SET column1 = value1, column2 = value2. WHERE condition;. Note Be careful when updating records in a table. UPDATE Table. The following SQL statement updates the first customer CustomerID = 1 with a new contact person and a new city. UPDATE Multiple Records.

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