Prepared by The Smartpath Information Systems www.thesmartpath.in BASIC RDBMS CONCEPTS Prepared by The Smartpath Information Systems www.thesmartpath.in

Index what is RDBMS Database concepts Explanation Database three tier architecture Relational Model E-R Diagram E-R Diagram (Explanation) Rules for RDBMS Keys in RDBMS Keys in RDBMS(continue) SQL in RDBMS Basic Datatypes in SQL

Index Operators in SQL - Arithmetic Operators in SQL - Comparison Operators in SQL - Logical Operator with Examples - comparison operator Operator with Examples - LIKE operator Operator with Examples - AND operator Operator with Examples - IN operator RDBMS Databases - MYSQL RDBMS Databases - MS SQL Server RDBMS Databases - Oracle

What is RDBMS RDBMS - Relational Database Management System It is database management system based on relational model , which is used to manage relational database. Relational model is organization of data in tables which are interrelated. Relational Database It is organized collection of tables. Data is stored in tables. Tables are related to each other using one or more fields. .

Database concepts Table A table is collection of rows and columns. In RDBMS table is called Relation and rows are called as tuple. Record A single row in a table is called record. It is also referred as tuple. It is a collection of fields. Column It is collection of field values of same type. Field It contains data. The smallest entity of table is field.

Explanation For Example table STUDENT Row column student_id Student_name marks 1101 abc 80 1101 Abc 80 Student_id 1101 1102

Database three tier architecture

Relational model In relational model , each table is related to every other table in database. There is one common field in tables which is used to relate them. Dept_no field that relates department table and professor table.

E-R Diagram The Entity Relationship Diagram

Explanation Entity An Entity represents a real world thing. For example student and class are entities. In E-R diagram rectangle shape is used to represent entity. Attribute The characteristics of an entity are called attributes. Student is entity . It has name , id , course he/she opts for are attributes. first_name Student

Explanation Relationship It describes how two entities are related to each other Enrolls in Class key attribute It is the main characteristic of an entity. It is used to relate tables student_name student_id key attribute Student Student

Rules for RDBMS Codd's twelve rules are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS)They are sometimes referred to as "Codd's Twelve Commandments". A DBMS is said to be Relational Database management If it follows Codd’s rules. Practically all rules are not followed , but RDBMS follows maximum of he Codd’s rules

Keys in RDBMS Primary Key An attribute that is used to access the table data is called primary key. It must Contain Unique values. It uniquely identifies a record in a table. Candidate Key It is set of attributes from which primary key is selected. One of them is made as Primary key and rest are candidate keys. They are candidate for primary key. It uniquely identifies a record. Composite key When more than one attributes are used to uniquely identify a record in a table It becomes composite key.

Keys in RDBMS Super Key It is a set of attributes that uniquely identifies each record in a table. It is a superset of candidate key. Secondary Key The candidate keys which are not selected as primary key , are called as secondary key or alternate key.

SQL in RDBMS Structure Query Language(SQL) is a programming language used for storing and managing data in RDBMS. SQL was the first commercial language introduced for E.F Codd's Relational model It is used to perform all types of database operations. Almost all database use SQL as standard language for manipulation of data. It is case sensitive language. SQL is set of three data languages. These are DDL - Data Definition Language. It is set of commands for defining table in database DCL - Data Control Language. It is set of commands used for controlling access to database DML - Data Manipulation Language. It is set of commands used to manipulate table data.

Basic Data types in SQL Char Takes Fixed length string 1 byte to 1000 bytes Varchar Takes variable length string 1 byte to 4000 bytes Varchar2 Number It stores fixed and floating point numbers up to 38 digit precision Date It stores date values in dd-mm-yy format as required Boolean It takes true or false value Only two values T or F

Operators in SQL - Arithmetic

Operators in SQL – comparison > Greater than Checks if the value of left operand is greater than the value of right operand (a > b) < Less than Checks if the value of left operand is less than the value of right operand (a < b) <> Not equal to Checks if are equal or not. (a <> b) = Equal to Checks if the values of two operands are equal. (a = b)

Operators in SQL - logical ALL The ALL operator is used to compare a value to all values in another value set. ANY The ANY operator is used to compare a value to any applicable value in the list according to the condition. BETWEEN The BETWEEN operator is used to search for values that are within a set of values, given the minimum value and the maximum value. IN The IN operator is used to compare a value to a list of literal values that have been specified. LIKE The LIKE operator is used to compare a value to similar values using wildcard operators.

Operators with examples Table student comparison operator <= SELECT student_name , stu_id from student where marks >= 85 output – David 1102 Student id Student name course marks 1101 John oca 80 1102 Rohit scjp 85 1103 Ramesh mca 82

Operators with examples Like operator SELECT * from student where student_name LIKE ‘r %’ ; * means all fields. output – 2 rows in which names begin with letter ‘r’ 1102 Rohit scjp 85 1103 Ramesh mca 82

Operators with examples AND operator – It is used to join two or more conditions. Output are the rows That satisfy all conditions given in statement SELECT student_id from student where marks > 80 AND student_name LIKE ‘r%’ ; output – we have given only one field to select i.e... Student id. Those student ids who have name begin with ‘r’ and marks greater than 80. 1102 1103

Operators with examples IN operator SELECT course from student where name IN (‘ramesh’ , ‘rohit’ ); It searches rows and takes only those values of course in which name is ramesh and rohit. Output Equivalently : SELECT course from student where name = ‘ramesh OR name = ‘rohit’; For multiple OR conditions we can use IN operator. SCJP MCA

RDBMS Databases The following Databases are Relational Database Management System MySQL MySQL is an open source SQL database, which is developed by Swedish company MySQL AB. MySQL supports many different platforms including Microsoft Windows, the major Linux distributions, UNIX, and Mac OS X. MySQL has free and paid versions , depending on its usage (non-commercial/commercial) and features. MySQL comes with a very fast, multi-threaded, multi-user, and robust SQL database server.

RDBMS Databases MS SQL Server Microsoft SQL Server is a relational database management system developed by Microsoft. As a database server, it is a software product with the primary function of storing and retrieving data as requested by other software applications which may run either on the same computer or on another computer across a network (including the Internet). MS SQL Server is a Relational Database Management System developed by Microsoft Inc. Its primary query languages are: T-SQL. ANSI SQL.

RDBMS Databases ORACLE It is a very large and multi-user database management system. Oracle is a relational database management system developed by 'Oracle Corporation'. Oracle works to efficiently manage its resource, a database of information, among the multiple clients requesting and sending data in the network. It is an excellent database server choice for client/server computing. Oracle supports all major operating systems for both clients and servers, including MSDOS, NetWare, UnixWare, OS/2 and most UNIX flavors.