Oracle Certification Questions

They both are used to replace characters in a string

MAX command is used to return maximum value from result setMAX 

Local :

Only available to the current Db connection for current user and are cleared when connection is closed.

Multiple users can’t share a local temporary table.

Global:

Available to any connection once created. They are cleared when the last connection is closed.

Can be shared by multiple user sessions

Data is organized in the form of row and columns, thus it is in tabular structure.

Alter database backup control file to trace

SQL statements are broadly classified into three. They are

1. DDL – Data Definition Language

DDL is used to define the structure that holds the data. For example, Create, Alter, Drop and Truncate table.

2. DML – Data Manipulation Language

DML is used for manipulation of the data itself. Typical operations are Insert, Delete, Update and retrieving the data from the table. The Select statement is considered as a limited version of the DML, since it can't change the data in the database. But it can perform operations on data retrieved from the DBMS, before the results are returned to the calling function.

3. DCL – Data Control Language

DCL is used to control the visibility of data like granting database access and set privileges to create tables, etc. Example - Grant, Revoke access permission to the user to access data in the database.

A primary key is a special relational database table column or combination of columns designated to uniquely identify all table records. That is, A primary key is a column or set of columns in a table that uniquely identifies tuples (rows) in that table.

A primary key, also called a Primary Keyword.

Main Features Primary key are ::

It must contain a unique value for each row of data.

It cannot contain null values.