Oracle sql updating multiple tables

07 Mar

Let me rewrite our query to illustrate this: SELECT FN. If both value and replacement_value are null, NVL will return null. fn.friend_id = fp.friend_id) records in both tables must satisfy the condition to appear in our resultset.And complicating things further, we can only tell which number belongs to which friend by looking in the FRIEND_PHONE table. We could, of course, get the information by running a series of queries: one select to find our friends’ names and their friend_id; a second to find the phone_id of the phone number linked to each friend in FRIEND_PHONE; and a third query to find the number from PHONE_NUMBER using the phone_id we identified in our second query. But hey, you can probably ride a unicycle across Siberia – but that didn’t stop them from inventing the car. We need a select statement that can query multiple tables at the same time. These articles might be good, but you may as well be reading a Dan Brown novel if you don’t put what you’re learning into practise). ”) If you’re up for a challenge, why don’t you add a few more layers to our query? Next time we’ll look at PL/SQL – functions and procedures.

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First off: The Oracle UPDATE statement is a part of the Oracle DDL (Data Definition Language) that can be used to alter the content or structure of a table in our database.Let us start simple, and pretend that the department with id # 20, “Marketing” is from now on going to be named “Customer Relations”.But, at the same time they were going to be under management of manager id # 205.These tables were both filled a few columns at the time to achieve the goal.Anyhow, in this example, let’s pretend we are going to build a summarized table with order totals for our customers.You’ve probably already guessed that I’m setting you up, but it’s important that we make these mistakes now, so we can learn about them. But what if Rachel had told us that she was changing her phone number next month and we’d put in a future end-date? The above query will give you many, many rows that look identical; however, if you replace the column list with an asterisk (*) and rerun the query, you’ll notice that the records aren’t exactly identical, each has one column different. PHONE_ID; in our select list) exist in two or more of our tables, we must always tell Oracle which one we are referring to every time we use that column name. Excluding all end-dated rows now would give us the wrong result. But we don’t want to hard-code the date into our query, in case we want to rerun the query next week. I have one table A has column (id, field_1,field_2), and another table B has column (id,field_2) Now I want to merge table B to A, that means i want to update field_2 in table A to value of table B. BTW I am using oracle Thanks Now, each time the above is executed, it will do it across all rows in the table.If this is something you need to do all the time, I would suggest something else, but for a one-off or very small tables it should be sufficient.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.