Sunday, October 18, 2015

SQL WHERE AND & OR Operators Syntax ORDER BY Keyword

SELECT column_name,column_name
FROM table_name
WHERE column_name operator value;


Below is a selection from the "Customers" table:
CustomerID CustomerName ContactName Address City PostalCode Country
1 Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4 Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden


WHERE Clause Example

The following SQL statement selects all the customers from the country "Mexico", in the "Customers" table:

Example

SELECT * FROM Customers
WHERE Country='Mexico';


CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry
Ana Trujillo Emparedados y helados  Ana Trujillo  Avda. de la Constitución 2222  México D.F.  05021  Mexico 
Antonio Moreno Taquería  Antonio Moreno  Mataderos 2312  México D.F.  05023  Mexico 

AND & OR Operators

Example

SELECT * FROM Customers
WHERE Country='Germany'
AND City='Berlin'; 
Number of Records: 1
CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry
Alfreds Futterkiste  Maria Anders  Obere Str. 57  Berlin  12209  Germany 

OR Operator Example

The following SQL statement selects all customers from the city "Berlin" OR "München", in the "Customers" table: 

Example

SELECT * FROM Customers
WHERE City='Berlin'
OR City='München'; 

Number of Records:
CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry
Alfreds Futterkiste  Maria Anders  Obere Str. 57  Berlin  12209  Germany 








Combining AND & OR

You can also combine AND and OR (use parenthesis to form complex expressions).
The following SQL statement selects all customers from the country "Germany" AND the city must be equal to "Berlin" OR "München", in the "Customers" table:

Example

SELECT * FROM Customers
WHERE Country='Germany'
AND (City='Berlin' OR City='München');

SQL ORDER BY Syntax

SELECT column_name, column_name
FROM table_name
ORDER BY column_name ASC|DESC, column_name ASC|DESC;


ORDER BY Example

The following SQL statement selects all customers from the "Customers" table, sorted by the "Country" column:

Example

SELECT * FROM Customers
ORDER BY Country;


ORDER BY DESC Example

The following SQL statement selects all customers from the "Customers" table, sorted DESCENDING by the "Country" column:

Example

SELECT * FROM Customers
ORDER BY Country DESC;


ORDER BY Several Columns Example

The following SQL statement selects all customers from the "Customers" table, sorted by the "Country" and the "CustomerName" column:

Example

SELECT * FROM Customers
ORDER BY Country, CustomerName;
 

ORDER BY Several Columns Example 2

The following SQL statement selects all customers from the "Customers" table, sorted ascending by the "Country" and descending by the "CustomerName" column:

Example

SELECT * FROM Customers
ORDER BY Country ASC, CustomerName DESC;
 

SQL SELECT DISTINCT Syntax

SQL SELECT DISTINCT Syntax

SELECT DISTINCT column_name,column_name
FROM table_name;
 
"Customers" table:
CustomerID CustomerName ContactName Address City PostalCode Country
1
Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4
Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden

Example

SELECT DISTINCT City FROM Customers;
 

SQL Quereis SELECT * FROM Customers;

"Customers" table:

CustomerID CustomerName ContactName Address City PostalCode Country
1
Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4
Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden
The table above contains five records (one for each customer) and seven columns (CustomerID, CustomerName, ContactName, Address, City, PostalCode, and Country).

Some of The Most Important SQL Commands

  • 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
  • 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 following SQL statement selects all the records in the "Customers" table:

 SELECT * FROM Customers; 

SQL is NOT case sensitive: select is the same as SELECT

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

SQL SELECT Syntax

SELECT column_name,column_name
FROM table_name;
 
SELECT * FROM table_name;
 

SELECT Column Example

The following SQL statement selects the "CustomerName" and "City" columns from the "Customers" table:

Example

SELECT CustomerName,City FROM Customers;
 

SELECT * Example

The following SQL statement selects all the columns from the "Customers" table:

Example

SELECT * FROM Customers;

Monday, March 2, 2015

PHP MySQL HTML Code: Create database & Create Table, Add, edit Search...

PHP MySQL HTML Code: Create database & Create Table, Add, edit Search...: create database DBname; CREATE TABLE people (name VARCHAR(30), age INTEGER, height FLOAT, date DATETIME); INSERT INTO people VALUES (...

Create database & Create Table, Add, edit Search Delete in MySQL

create database DBname;
CREATE TABLE people (name VARCHAR(30), age INTEGER, height FLOAT, date DATETIME);

INSERT INTO people VALUES ( "Jim", 45, 1.75, "2006-02-02 15:35:00" ), ( "Peggy", 6, 1.12, "2006-03-02 16:21:00" )

UPDATE people SET age = 7, date = "2006-06-02 16:21:00", height = 1.22 WHERE name = "Peggy"
SELECT name FROM people WHERE age < 12
DELETE FROM people WHERE age < 12


Friday, February 6, 2015

Open a Connection to MySQL

<?php
$servername = "localhost";
$username = "username";
$password = "password";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);

echo "Connected successfully";
?>

Thursday, January 29, 2015

HTML Comment

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