How to delete contents in two tables at a time? When you delete contents in one table then other table contents should also be deleted.
Latest Answer: You may also use triggers for this purpose. But specifying on delete cascade while defining foreign key constraint is better option. ...
How to insert a record in two tables with single insert statement ?
Latest Answer: Using merge concept, we can insert a record at a time into two tables. ...
How to export data from a SQL table to MS Excel?
Latest Answer: using UTL_FILE ...
How to execute DOS Commands from SQL prompt?
Latest Answer: Either you can type HOST to go into DOS prompt, use DOS commands and then type EXIT to return back.OR, if you want to run only one DOS command you can type HOST Hope this will work for u. ...
How to handle the table level locks and column level locks?
Latest Answer: When you are performing INSERT , DELETE , UPDATE operations on a table it implicity aquires row level locks. If a transaction obtains a row lock for a row, the transaction also aquires a table lock for the corresponding table to prevent conflicting ...
What is CBO and RBO? What is diff between these two?
Latest Answer: The job of optimizer is to decide the most efficient method to execute a
query.
There are two types of optimizers in oracle
RBO or Rule Based Optimizer since v6
CBO or Cost Based Optimizer since v7
Rule based optimizer uses set of rules to decide ...
What is explain plan and what is tkproff?
How can you tune the query?
Latest Answer: First look at the explain plan if there is any full scan. Then add appropriate index on columns that are used in the query. Basically, always add index on foreign key and the date columns (Most of the application access tables based on dated) ...
What is the use of Left Outer & Right Outer Join, Using Equi Join with Union we can do the outer join then why we need to go for Outer Join
Latest Answer: By using equi join and union we can get only matched data from both tables. But we can get unmatched data by using left outer join, and right outer join.Ex: select e.emp_name,e.salary, d.department_name from employees e, departments d where e.department_id ...
How to retrieve data from two tables of different servers
Latest Answer: Use DB link to get data from 2 different DB on 2 different server.For example, if there are 2 DB, DB1 and DB2 Then create a link with name “DB2” in DB1.After that you can query DB2 tables In DB1, you can do Select * from EMP e, dept@DB2 ...
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