SQL Tutorial-Indx

SQL Basic	SQL Advanced	SQL Functions
·     Introduction to SQL ·     SQL Syntax ·     SQL SELECT Statement ·     SQL SELECT DISTINCT Statement ·     SQL AND & OR Operators ·     SQL WHERE Clause ·     SQL ORDER BY Keyword ·     SQL INSERT INTO Statement ·     SQL UPDATE Statement ·     SQL DELETE Statement	·     SQL TOP Clause ·     SQL LIKE Operator ·     SQL Wildcards ·     SQL BETWEEN Operator ·     SQL IN Operator ·     SQL Joins ·     SQL INNER JOIN Keyword ·     SQL LEFT JOIN Keyword ·     SQL RIGHT JOIN Keyword ·     SQL FULL JOIN Keyword ·     SQL UNION Operator ·     SQL SELECT INTO Statement ·     SQL CREATE DATABASE Statement ·     SQL Constraints ·     The CREATE TABLE Statement ·     SQL NOT NULL Constraint ·     SQL UNIQUE Constraint ·     SQL PRIMARY KEY Constraint ·     SQL FOREIGN KEY Constraint ·     SQL FOREIGN KEY Constraint ·     SQL CHECK Constraint ·     SQL DEFAULT Constraint ·     SQL DEFAULT Constraint ·     SQL CREATE INDEX Statement ·     SQL DROP INDEX, DROP TABLE, and DROP DATABASE ·     SQL ALTER TABLE Statement ·     SQL AUTO INCREMENT Field ·     SQL Views ·     SQL Date Functions ·     SQL NULL Values ·     SQL NULL Functions ·     SQL Data Types ·	·     SQL Functions ·     SQL AVG() Function ·     SQL COUNT() Function ·     SQL FIRST() Function ·     SQL LAST() Function ·     SQL MAX() Function ·     SQL MIN() Function ·     SQL SUM() Function ·     SQL GROUP BY Statement ·     SQL HAVING Clause ·     SQL UCASE() Function ·     SQL LCASE() Function ·     SQL MID() Function ·     SQL LEN() Function ·     SQL ROUND() Function ·     SQL NOW() Function ·     SQL FORMAT() Function ·     SQL Quick Reference

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Introduction to SQL

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

SQL is a Standard - BUT....

Although SQL is an ANSI (American National Standards Institute) standard, there are many different 
versions of the SQL language.


However, to be compliant with the ANSI standard, they all support at least the major commands (such 
as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar manner.


Note: Most of the SQL database programs also have their own proprietary extensions in addition to the 
SQL standard!

Using SQL in Your Web Site

To build a web site that shows some data from a database, you will need the following:

• An RDBMS database program (i.e. MS Access, SQL Server, MySQL)
• A server-side scripting language, like PHP or ASP
• SQL
• HTML / CSS

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.

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SQL Syntax

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).

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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

In this tutorial we will teach you all about the different SQL statements.

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Keep in Mind That...

• SQL is not case sensitive

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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.

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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

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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.

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An SQL SELECT Example

The "Persons" table:

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

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SELECT * Example

Now we want to select all the columns from the "Persons" table.
We use the following SELECT statement: 

SELECT * FROM Persons

Tip: The asterisk (*) is a quick way of selecting all columns!
The result-set will look like this:

P_Id	LastName	FirstName	Address	City
1	Hansen	Ola	Timoteivn 10	Sandnes
2	Svendson	Tove	Borgvn 23	Sandnes
3	Pettersen	Kari	Storgt 20	Stavanger

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