Updating two tables in oracle Two way video chat xxx

Posted by / 17-Jun-2018 12:48

Updating two tables in oracle

First table ("names") Well, there is an immediate advantage in performing just a single SQL query instead of two, and I believe it is quite clear: the server will have a lighter work load.

At the same time, we will have a full control on the performed operation, which will be faster and easier to maintain.

The other thing I'm doing is a "concat" to the meter number.

The user can have 1 character value in the first position of the meter number.

Let's just say I have a header and a detail record.

The user keys the first record of data, along with how many duplications they would like to make of the current record.

One of the things they built in the database is this program called the optimizer.

The optimizer's job is to take SQL statements and decide how to get the data that is being asked for in the SQL statement and how to get it in the quickest way possible.

In the next section, we will show you how to generate statistics on tables and indexes in your database.

When a SQL statement is executed, the database must convert the query into an execution plan and choose the best way to retrieve the data.

For Oracle, each SQL query has many choices for execution plans, including which index to use to retrieve table row, what order in which to join multiple tables together, and which internal join methods to use (Oracle has nested loop joins, hash joins, star joins, and sort merge join methods).

An execution plan is like a set of instructions that tells Oracle how to go and get the data. In it, the optimizer tells Oracle to first go get all the rows of the EMP department, and then sort those rows (Reading an execution plan is somewhat of an art, so trust us on this one, the full scan of the EMP table is first).

Did you notice in the plan that there is a column called ROWS?

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SQL select * from emp 2 / ID FNAME LNAME START_DAT END_DATE SALARY CITY ---- ---------- ---------- --------- --------- ---------- ---------- DESCRIPTION --------------- 01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester ID FNAME LNAME START_DAT END_DATE SALARY CITY ---- ---------- ---------- --------- --------- ---------- ---------- DESCRIPTION --------------- 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester ID FNAME LNAME START_DAT END_DATE SALARY CITY ---- ---------- ---------- --------- --------- ---------- ---------- DESCRIPTION --------------- 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected.

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