Oracle sql updating multiple tables

Doing a 'join update' in Oracle can sometime cause a few headaches.

By 'join update' I mean the situation where we have two tables and want to update some of the rows in the first table based on values that exist in the second table.

UPDATE dest_tab tt SET (tt.code, tt.description) = (SELECT st.code, st.description FROM source_tab st WHERE = tt.id) WHERE EXISTS (SELECT 1 FROM source_tab WHERE id = tt.id); 5000 rows updated.

SQL ----------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ----------------------------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | 4999 | 185K| 30013 (34)| | | 1 | UPDATE | dest_tab | | | | | | 2 | NESTED LOOPS SEMI | | 4999 | 185K| 19 (6)| | | 3 | TABLE ACCESS FULL | dest_tab | 10000 | 332K| 18 (0)| | |* 4 | INDEX UNIQUE SCAN | source_tab_PK | 2500 | 10000 | 0 (0)| | | 5 | TABLE ACCESS BY INDEX ROWID| source_tab | 1 | 43 | 2 (0)| | |* 6 | INDEX UNIQUE SCAN | source_tab_PK | 1 | | 1 (0)| | ----------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 4 - access("ID"="TT"."ID") 6 - access("ST"."ID"=: B1) UPDATE (SELECT tt.id, tt.code, tt.description, AS st_code, st.description AS st_description FROM dest_tab tt, source_tab st WHERE = st.id) ilv SET = ilv.st_code, ilv.description = ilv.st_description; 5000 rows updated.

If we consider what we’ve learned so far – Select, Update, Insert, Delete – as unicellular organisms, what we’re about to do next is multicellular, big and beautiful – it’s like going from an amoeba to a bee, a butterfly, to Beyoncé. Notice how, by using a left outer join, we got all the rows in friend_name (the table on the left of the join); change it to a right outer join and see how that changes the output. But we need to add a third table – PHONE_NUMBER – to our query to make it useful. Joining multiple tables in this way is a little like baking a cake; you apply your joins layer by layer.

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The syntax for a multi-table select statement is as follows: Run that and see what you get. However, when I run the query, I get 2 rows for Rachel – one for her current phone number and another for her previous one. Of course we can simply add to our column list and look to see which record is current. END_DATE IS NULL” to our Where clause and exclude end-dated rows in that way. Expand the query to display our friends’ addresses: to do this you’ll need to join the FRIEND_ADDRESS and ADDRESS tables. Part 1, Part 2, Part 3 A wise man* once said: To build the Great Wall of China, you must start with a brick. Value and replacement­_value can be of whichever datatype you like. However, with an outer join we can ask Oracle to impose our rule on one of our tables and return nulls whenever the other table fails the test.In our previous articles we acquainted ourselves with our bricks; now it’s time to build. In other words, we can say, we want to see all of our friends (all records in friend_name), and we don’t mind seeing nulls whenever they don’t have a phone number.However, when I ran the UPDATE query it updated 210 rows. This would update other addresses associated that contact ID has as well. Question: I want to update multiple rows in my table, and I need to understand how to update multiple columns.

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