| Introduction to SQL
As we know from last chapter that SQL is a standard language for accessing and manipulating databases. Here we will cover what is SQL and What we can do with SQL and some information about RDBMS.
No first know What is SQL?
SQL basically stands for mainly is Structured Query Language
SQL helps in accessing and manipulate databases
SQL become standard of ANSI in 1986 and ISO in 1987
Now we go to what we can do with SQL
We can retrieve data from a database tables
We can insert records in database tables
We can update records in database tables
We can delete records from a database tables
We can create new tables, database, views and stored procedures
We can create views in databases
We can set permissions on tables and another part of databases
We can do different filters and queries on the databases
Now we will Cover what is RDBMS
As we all know RDBMS stands for Relational Database Management System.
RDBMS is basis for all modern database system like MS SQL Server,IBM DB2, Oracle, MySQL and Access.
RDBMS stored data in database objects which is called tables. And this tables is a collection of related data entries which consists of columns and rows.
To under stand tables we take a example of below student tables
Id-------Name---------Age--------Sex
1-------Kamal--------15----------M
2-------Rita-----------14----------F
3-------Adam---------14----------M
4-------Stef-----------15----------F
Now comes to tables part
table is broken up into smaller entities which is called fields.The fields in the student table consist of Id, Name, Age and Sex. A field is a column in a table which is designed to maintain a specific information on each record in the table.
We can also called record as a row which is every individual entry that exists in a table. A record is a horizontal entity in a table.
On the other column is a vertical entity in a table what have all the information associated with specific field in table. | | |