Oracle SQL in 10 Minutes - Asim Abbasi
CH1: SQL Basics | CH2: SQL Operators | CH3: SQL Built-in Functions | CH4: SQL Joins | CH5: UPDATE, INSERT & DELETE Statements | CH6: CREATE, ALTER & DROP Statements | CH7: Constraints | CH8: Linking Tables vs Joining Tables | CH9: SQL Statements for Other Database Objects | CH10: SQL Statements for Database Security
Chapter 1: SQL Basics
Once you see a database product saying its RDBMS it means it uses SQL as
a language and data inside it is written always in table form i.e.
rows/records & columns/fields. Moreover there may or may not be
relationship in-between those tables.
Each of the RDBMS Database manufacture has their own version of SQL. But
they all are more than 90% alike. If it takes you to learn Oracle SQL in
a week after that you can learn SQL for MS SQL server in less than an
hour. There is one SQL standard defined by ANSI (American National
Standard Institute) and is called ANSI SQL. Nearly all RDBMS database
manufacture incorporates this ANSI SQL and then builds a layer of some
new stuff on top of it to provide added functionality in the language.
The SQL that we will be learning in this book will be more precisely
Oracle SQL.
Concept of arranging the data in the form of table is very simple. We
have been doing it on the papers for years and the concept is still the
same. There are two terms that we will be using a lot. One is called “Record(s)”
or “Row(s)” and other one is called “Field(s)” or “Column(s)”. Like
shown in the figure below, there are 5 records in the table and 3
fields. Each field in Oracle table has been assigned a “Data type”.
While creating a table if you have assigned DOB (Date of Birth) field
“date” data type, you cannot insert characters in it or you cannot
insert numeric value in it. We will learn this stuff in great detail
when we learn about CREATE TABLE statement.
There is one more thing that we can do with fields, we can assign
constraints to them e.g. If you assign UNIQUE constraint to any column
then you would not be able to insert any value in it which is already
their in the same column. Constraints help in maintaining the data
integrity of the system.
Table Showing Records/Rows And Fields/Columns
________________________________________
SQL is nothing but a set of commands/statements and are categorized into
following five groups viz., DQL: Data Query Language, DML: Data
Manipulation Language, DDL: Data Definition Language, TCL: Transaction
Control Language, DCL: Data Control Language.
DQL: SELECT
DML: DELETE, INSERT, UPDATE
DDL: CREATE, DROP, TRUNCATE, ALTER
TCL: COMMIT, ROLLBACK, SAVEPOINT
DCL: GRANT, REVOKE
Once we finish up with SQL you will say to yourself, “Oh! That was
easy”. Let’s start with the following example.
SELECT name, phone, city
FROM address_book;
Chapter 1: Overview
CH1: SQL Basics | CH2:
SQL Operators |
CH3: SQL Built-in Functions | CH4:
SQL Joins | CH5:
UPDATE, INSERT & DELETE Statements |
CH6: CREATE, ALTER & DROP Statements | CH7:
Constraints | CH8:
Linking Tables vs Joining Tables | CH9:
SQL
Statements for Other Database Objects | CH10:
SQL Statements for
Database Security Share with others: