Sql tutorial - Lecture notes 5 PDF

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A guide on sql...

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SQL

About the Tutorial SQL is a database computer language designed for the retrieval and management of data in a relational database. SQL stands for Structured Query Language. This tutorial will give you a quick start to SQL. It covers most of the topics required for a basic understanding of SQL and to get a feel of how it works.

Audience This tutorial is prepared for beginners to help them understand the basic as well as the advanced concepts related to SQL languages. This tutorial will give you enough understanding on the various components of SQL along with suitable examples.

Prerequisites Before you start practicing with various types of examples given in this tutorial, I am assuming that you are already aware about what a database is, especially the RDBMS and what is a computer programming language.

Compile/Execute SQL Programs If you are willing to compile and execute SQL programs with Oracle 11g RDBMS but you don’t have a setup for the same, do not worry. Coding Ground is available on a high-end dedicated server giving you real programming experience. It is free and is available online for everyone.

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Table of Contents About the Tutorial ............................................................................................................................................ i Audience ........................................................................................................................................................... i Prerequisites ..................................................................................................................................................... i Compile/Execute SQL Programs ....................................................................................................................... i Copyright & Disclaimer ..................................................................................................................................... i Table of Contents ............................................................................................................................................ ii 1.

SQL ─ Overview ......................................................................................................................................... 1 What is SQL? .................................................................................................................................................... 1 SQL Process ..................................................................................................................................................... 2 SQL Commands ................................................................................................................................................ 3

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SQL ─ RDBMS Concepts ............................................................................................................................. 5 What is RDBMS? .............................................................................................................................................. 5 SQL Constraints ............................................................................................................................................... 6 Data Integrity ................................................................................................................................................... 7 Database Normalization .................................................................................................................................. 7 Database – First Normal Form (1NF) ............................................................................................................... 8 Database – Second Normal Form (2NF) ........................................................................................................ 10 Database – Third Normal Form (3NF) ............................................................................................................ 11

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SQL ─ RDBMS Databases ......................................................................................................................... 14 MySQL ........................................................................................................................................................... 14 MS SQL Server ............................................................................................................................................... 15 ORACLE .......................................................................................................................................................... 16 MS ACCESS..................................................................................................................................................... 17

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SQL – Syntax ...........................................................................................................................................19 Various Syntax in SQL .................................................................................................................................... 19

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SQL ─ Data Types .................................................................................................................................... 24

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SQL – Operators ...................................................................................................................................... 28 What is an Operator in SQL? ......................................................................................................................... 28 SQL Arithmetic Operators ............................................................................................................................. 28 Arithmetic Operators – Examples ................................................................................................................. 29 SQL Comparison Operators ........................................................................................................................... 30 Comparison Operators – Examples ............................................................................................................... 31 SQL Logical Operators ................................................................................................................................... 34 Logical Operators – Examples ........................................................................................................................ 35

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SQL – Expressions ...................................................................................................................................41 Boolean Expressions ...................................................................................................................................... 41 Numeric Expressions ..................................................................................................................................... 42 Date Expressions ........................................................................................................................................... 43

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SQL – CREATE Database .......................................................................................................................... 45

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SQL ─ DROP or DELETE Database ............................................................................................................. 46

10. SQL ─ SELECT Database, USE Statement .................................................................................................. 47 ii

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11. SQL ─ CREATE Table ................................................................................................................................48 SQL - Creating a Table from an Existing Table ............................................................................................... 49 12. SQL ─ DROP or DELETE Table ................................................................................................................... 51 13. SQL ─ INSERT Query ................................................................................................................................ 53 14. SQL ─ SELECT Query ................................................................................................................................56 15. SQL ─ WHERE Clause ............................................................................................................................... 59 16. SQL ─ AND & OR Conjunctive Operators ................................................................................................. 62 The AND Operator ......................................................................................................................................... 62 The OR Operator ........................................................................................................................................... 63 17. SQL ─ UPDATE Query .............................................................................................................................. 66 18. SQL ─ DELETE Query ................................................................................................................................ 69 19. SQL ─ LIKE Clause .................................................................................................................................... 72 20. SQL ─ TOP, LIMIT or ROWNUM Clause .................................................................................................... 76 21. SQL ─ ORDER BY Clause ........................................................................................................................... 79 22. SQL ─ Group By ....................................................................................................................................... 82 23. SQL ─ Distinct Keyword ........................................................................................................................... 86 24. SQL ─ SORTING Results ...........................................................................................................................89 25. SQL ─ Constraints .................................................................................................................................... 92 SQL - NOT NULL Constraint ........................................................................................................................... 92 SQL - DEFAULT Constraint ............................................................................................................................. 93 SQL - UNIQUE Constraint ............................................................................................................................... 94 SQL ─ Primary Key.......................................................................................................................................... 95 SQL ─ Foreign Key .......................................................................................................................................... 96 SQL ─ CHECK Constraint ................................................................................................................................ 98 SQL ─ INDEX Constraint ................................................................................................................................. 99 Dropping Constraints ................................................................................................................................... 101 Integrity Constraints .................................................................................................................................... 101 26. SQL ─ Using Joins .................................................................................................................................. 102 SQL - INNER JOIN ......................................................................................................................................... 103 SQL ─ LEFT JOIN ........................................................................................................................................... 105 SQL - RIGHT JOIN .........................................................................................................................................107 SQL ─ FULL JOIN ........................................................................................................................................... 109 SQL ─ SELF JOIN ...........................................................................................................................................111 SQL ─ CARTESIAN or CROSS JOIN ................................................................................................................. 113 27. SQL ─ UNIONS CLAUSE .......................................................................................................................... 116 The UNION ALL Clause................................................................................................................................. 119 SQL ─ INTERSECT Clause .............................................................................................................................. 121 SQL ─ EXCEPT Clause ................................................................................................................................... 123 iii

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28. SQL ─ NULL Values ................................................................................................................................127 29. SQL ─ Alias Syntax ................................................................................................................................. 130 30. SQL – Indexes ........................................................................................................................................ 134 The CREATE INDEX Command ..................................................................................................................... 134 The DROP INDEX Command ........................................................................................................................135 SQL - INDEX Constraint ................................................................................................................................ 135 31. SQL ─ ALTER TABLE Command .............................................................................................................. 138 32. SQL - TRUNCATE TABLE Command ........................................................................................................ 142 33. SQL ─ Using Views ................................................................................................................................. 143 Creating Views ............................................................................................................................................. 143 The WITH CHECK OPTION ............................................................................................................................ 144 34. SQL ─ Having Clause .............................................................................................................................. 148 35. SQL – Transactions ................................................................................................................................ 151 Properties of Transactions ........................................................................................................................... 151 Transactional Control Commands ............................................................................................................... 151 36. SQL ─ Wildcard Operators ..................................................................................................................... 158 37. SQL ─ Date Functions ............................................................................................................................162 38. SQL ─ Temporary Tables........................................................................................................................ 192 What are Temporary Tables? ...................................................................................................................... 192 Dropping Temporary Tables ........................................................................................................................ 193 39. SQL – Clone Tables ................................................................................................................................ 194 40. SQL – Sub Queries ................................................................................................................................. 197 Subqueries with the SELECT Statement ...................................................................................................... 197 Subqueries with the INSERT Statement ...................................................................................................... 198 Subqueries with the UPDATE Statement ..................................................................................................... 199 Subqueries with the DELETE Statement ...................................................................................................... 200 41. SQL – Using Sequences..........................................................................................................................202 Using AUTO_INCREMENT column ............................................................................................................... 202 Obtain AUTO_INCREMENT Values .............................................................................................................. 203 Renumbering an Existing Sequence ............................................................................................................ 203 Starting a Sequence at a Particular Value ................................................................................................... 204 42. SQL – Handling Duplicates ....................................................................................................................206 43. SQL – Injection ...................................................................................................................................... 209 Preventing SQL Injection .............................................................................................................................210

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1. SQL ─ Overview

SQL is a language to operate databases; it includes database creation, deletion, fetching rows, modifying rows, etc. SQL is an ANSI (American National Standards Institute) standard language, but there are many different versions of the SQL language.

What is SQL? SQL is Structured Query Language, which is a computer language for storing, manipulating and retrieving data stored in a relational database. SQL is the standard language for Relational Database System. All the Relational Database Management Systems (RDMS) like MySQL, MS Access, Oracle, Sybase, Informix, Postgres and SQL Server use SQL as their standard database langu...