SQL introduction
Hey everyone, today’s topic is Introduction to SQL. In this article we’ll learn about basics of SQL. let’s get started.
Table of Contents
What is SQL
SQL Stands for Structured Query Language. It allow us to accessing and manipulating databases. so basically SQL is a programming language used to manage relational databases. It is a standard language for Relational Database management System(RDBMS). By using it you can create, read, update and delete relational databases and tables. So Before moving on we have to know about RDBMS.
RDBMS
As we knew RDBMS is stands for Relational Database Management System. RDBMS organizes the data or information in to form of tables. It looks like Excel spreadsheet. The table is a collection of related data entries that is organized into a rows and columns. Each column holds a particular type of value.
let’s take an example:
StudentIDStudentNameStudentClassStudentAgeStudentMarks1001Thomas HardyMCA2470%1002Ana TrujilloMBA2565%1003Hanna MoosBCA2169%1004Patricio SimpsonB.Com2383%1005Ann DevonBBA2075%Student
As we had a table of information about Students. In the table, Every table is broken up into smaller entities called fields. The fields in the Student table consist of StudentId, StudentName, StudentClass, StudentAge and StudentMarks. Field is a column in a table that is Used to maintain specific information about every record in the table. Each column contains a particular type of value.
Each row in the table contains piece of information and can be used to extract data from this row for use. Columns are the vertical entities in a table and rows are the horizontal entities in a table.
SQL Process
- When an Structured Query Language command is executing for any RDBMS, then the system figure out the best way to carry out the request and the Structured Query Language engine determines that how to interpret the task.
- In the process, various components are included. These components can be optimization Engine, Query engine, Query dispatcher, classic, etc.
- All the non-SQL queries are handled by the classic query engine, but SQL query engine won’t handle logical files.
Rules:
SQL follows the following rules:
- Structure query language is not case sensitive. In general, keywords of SQL are written in uppercase.
- Statements of SQL are based on text lines. We can use a single SQL statement on one or multiple text line.
- Using the SQL statements, we can perform most of the actions in a database.
- SQL depends on tuple relational calculus and relational algebra.
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