Class notes
Sql full course from basics onwards
- Course
- Institution
Providing in depth content of SQL from basics onwards
[Show more]
Seller
Follow
sudarsanbathala
Content preview
INTRODUCTIONSQL is a standard language for accessing databases.
how to use SQL to access and manipulate data in:
MySQL, SQL Server, Access, Oracle, Sybase, DB2, and other database systems.
SQL Syntax:
SELECT Company, Country FROM Customers WHERE Country <> 'USA'
SQL Result:
Company Country
Island Trading UK
Galería del gastrónomo Spain
Laughing Bacchus Wine Cellars Canada
Paris spécialités France
Simons bistro Denmark
Wolski Zajazd Poland
SQL is a “standard language for accessing and manipulating databases”.
What is SQL?
SQL stands for Structured Query Language
SQL lets you access and manipulate databases
SQL is an ANSI (American National Standards Institute) standard
What Can SQL do?
SQL can execute queries against a database
SQL can retrieve data from a database
SQL can insert records in a database
SQL can update records in a database
SQL can delete records from a database
SQL can create new databases
SQL can create new tables in a database
SQL can create stored procedures in a database
SQL can create views in a database
SQL can set permissions on tables, procedures, and views
2
,RDBMS
RDBMS stands for Relational Database Management System.
RDBMS is the basis for SQL, and for all modern database systems like MS SQL Server, IBM
DB2, Oracle, MySQL, and Microsoft Access.
The data in RDBMS is stored in database objects called tables.
A table is a collections of related data entries and it consists of columns and rows.
SQL BASICS
Database Tables
A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers"
or "Orders"). Tables contain records (rows) with data.
Below is an example of a table called "Persons":
P_Id LastName FirstName Address City
1 Hansen Ola Timoteivn 10 Sandnes
2 Svendson Tove Borgvn 23 Sandnes
3 Pettersen Kari Storgt 20 Stavanger
The table above contains three records (one for each person) and five columns (P_Id, LastName,
FirstName, Address, and City).
SQL Statements
Most of the actions you need to perform on a database are done with SQL statements.
The following SQL statement will select all the records in the "Persons" table:
SELECT * FROM Persons
Note:
SQL is not case sensitive
Semicolon after SQL Statements?
Some database systems require a semicolon at the end of each SQL statement.
Semicolon is the standard way to separate each SQL statement in database systems that allow
more than one SQL statement to be executed in the same call to the server.
We are using MS Access and SQL Server 2000 and we do not have to put a semicolon after each
SQL statement, but some database programs force you to use it.
3
,SQL DML and DDL
SQL can be divided into two parts: The Data Manipulation Language (DML) and the Data Definition
Language (DDL).
The query and update commands form the DML part of SQL:
SELECT - extracts data from a database
UPDATE - updates data in a database
DELETE - deletes data from a database
INSERT INTO - inserts new data into a database
The DDL part of SQL permits database tables to be created or deleted. It also define indexes (keys),
specify links between tables, and impose constraints between tables. The most important DDL statements
in SQL are:
CREATE DATABASE - creates a new database
ALTER DATABASE - modifies a database
CREATE TABLE - creates a new table
ALTER TABLE - modifies a table
DROP TABLE - deletes a table
CREATE INDEX - creates an index (search key)
DROP INDEX - deletes an index
The SQL SELECT Statement
The SELECT statement is used to select data from a database.
The result is stored in a result table, called the result-set.
SQL SELECT Syntax
SELECT column_name(s)
FROM table_name
And
SELECT * FROM table_name
Note: SQL is not case sensitive. SELECT is the same as select.
An SQL SELECT Example
The "Persons" table:
4
, P_Id LastName FirstName Address City
1 Hansen Ola Timoteivn 10 Sandnes
2 Svendson Tove Borgvn 23 Sandnes
3 Pettersen Kari Storgt 20 Stavanger
Now we want to select the content of the columns named "LastName" and "FirstName" from the table
above.
We use the following SELECT statement:
SELECT LastName,FirstName FROM Persons
The result-set will look like this:
LastName FirstName
Hansen Ola
Svendson Tove
Pettersen Kari
SELECT * Example
Now we want to select all the columns from the "Persons" table.
We use the following SELECT statement:
SELECT * From Persons
The SQL SELECT DISTINCT Statement
In a table, some of the columns may contain duplicate values. This is not a problem, however,
sometimes you will want to list only the different (distinct) values in a table.
The DISTINCT keyword can be used to return only distinct (different) values.
SQL SELECT DISTINCT Syntax
SELECT DISTINCT column_name(s)
FROM table_name
SELECT DISTINCT Example
The "Persons" table:
P_Id LastName FirstName Address City
1 Hansen Ola Timoteivn 10 Sandnes
5
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller sudarsanbathala. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79223 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now