Simple Queries in SQL

Queries are one of a thing that make database powerful. The "Query" refers to action of retrieving data from the database. There are following some common clauses used in SQL. SELECT :- SELECT clause used to retrieves data from the table. SELECT command also provides the query capability this means that executing SELECT statement, information …

Nested Queries of SQL

This nested queries is in the SQL SELECT statement inside another SELECT or action query. The SQL first evaluates the inner query. The result of an inner query is returned to the outer query. Syntax SELECT EMPLOYEE_NAME FROM EMPLOYEE WHERE DEPT_code=select DEPT_code FROM EMPLOYEE WHERE EMPLOYEE_name='<'raju'>'; There are following some operators used in nested query. …

Datatypes of SQL

Every field or column in a table is given the database, when table is defined there data types describe a kind of information that can be store in a column. The most common datatypes are: CHAR (size) :- The column defied with CHAR datatype is allowed to store all types of character including letters both …

SQL

Structure Query Language :- SQL is a language. It is provides an interface to relational database system. SQL was developed by IBM in 1970 used to store and manage data in relational database management system. SQL also used to preform all types of operation likes, Inserting, Updating, Deleting, Creating and Modifying tables. Processing capabilities of …

Function Dependencies

Function dependencies are the consequence of a interrelationship among attribute of an entity represented by a relation. Function dependencies may also be due to the relationship between entities that are also represented by a relation. A relation R, attribute Y of R is a function dependencies. An attribute X of R if and only if each X value on …

Aggregate Function

Aggregate function produce a single value for the entire group of table entries. An aggregate or column function also be used with the SELECT command. SUM :- SUM function calculates the arithmetic sum of all selected values of a given columns. For example, to find the SUM of BASIC salary from the EMPLOYEE table. SELECT SUM …

Relational Algebra

Introduction :- Relational algebra is a collection of operation to manipulate relational. It consist a set of operation that take one or more relations as input and produre new relation as their result. The relational algebra operations can be divided into basic set-oriented operation like union, difference, intersection, cartesion product, and relational-oriented operation like join, …

E-R Model

Introduction :- E-R Model is also called Entity-Relationship Model. It is a high level conceptual data model developed by Peter den in 1976 to facilitate database design. The conceptual data model is a data of concepts that describe the structure of a database and associated retrieval ans updating transaction on the database. Basic terms of …