Data in database can be manipulated, accessed or added if the description of the stored data objects is provided. Every database system must provide description of the available user data…
Category: <span>DBMS</span>
PL/SQL architecture defines how the PL/SQL blocks are executed in Oracle. Oracle provides PL/SQL engine that executes the Procedural Language part of a block. When an application program or a…
An important aspect of database systems is creation of external schemas for different users and their needs. These are also known as external views for users. One way of doing…
Subquery in SQL or nesting a query within another query is an extremely important concept in SQL. It allows the programmer to fetch rows from one table depending upon the…
SQL UNION, UNION ALL, INTERSECT and MINUS are set operations to help you to get the required data from multiple tables. It is basically application of Set Theory formulas on…
A Join is a powerful tool in SQL for joining multiple tables and extracting data beyond the results returned by simple SQL SELECT using one table. In addition to Inner…
Individual tables in a database are not enough. The most common need of database is to access data from multiple tables. SQL Join is the way to fulfill the need…
In database systems many times you need to summarize the data stored in tables in answer to adhoc queries of the users. For this SQL Aggregate Functions can be used.…
Why Database Recovery Techniques are important?
Database are prone to failures due to inconsistency, network failure, errors or any accidental damage. Reliable database recovery techniques are highly important to bring a database back into a working state after a failure. Recovery includes the procedures of restoring database to the earlier and previously existing condition.
