• php
  • 3577
  • 20-3-2008
    • A database holds one or multiple tables. -------------------------------------------------------------------------------- [color=FA0309]Create a Database[/color]
    The CREATE DATABASE statement is used to create a database in MySQL. [color=FA0309]Syntax[/color]
    CREATE DATABASE database_name
    To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection. [color=FA0309]Example[/color]
    In the following example we create a database called "my_db":
    <?php
    $con = mysql_connect("localhost","peter","abc123");
    if (!$con)
    {
    die('Could not connect: ' . mysql_error());
    }if (mysql_query("CREATE DATABASE my_db",$con))
    {
    echo "Database created";
    }
    else
    {
    echo "Error creating database: " . mysql_error();
    }
    mysql_close($con);
    ?>
    -------------------------------------------------------------------------------- [color=FA0309]Create a Table[/color]
    The CREATE TABLE statement is used to create a database table in MySQL. [color=FA0309]Syntax[/color]
    CREATE TABLE table_name
    (
    column_name1 data_type,
    column_name2 data_type,
    column_name3 data_type,
    .......
    )
    We must add the CREATE TABLE statement to the mysql_query() function to execute the command. [color=FA0309]Example[/color]
    The following example shows how you can create a table named "person", with three columns. The column names will be "FirstName", "LastName" and "Age":
    <?php
    $con = mysql_connect("localhost","peter","abc123");
    if (!$con)
    {
    die('Could not connect: ' . mysql_error());
    }
    // Create database
    if (mysql_query("CREATE DATABASE my_db",$con))
    {
    echo "Database created";
    }
    else
    {
    echo "Error creating database: " . mysql_error();
    }
    // Create table in my_db database
    mysql_select_db("my_db", $con);
    $sql = "CREATE TABLE person
    (
    FirstName varchar(15),
    LastName varchar(15),
    Age int
    )";
    mysql_query($sql,$con);
    mysql_close($con);
    ?>
    Important: A database must be selected before a table can be created. The database is selected with the mysql_select_db() function. [color=FA0309]Note:[/color] When you create a database field of type varchar, you must specify the maximum length of the field, e.g. varchar(15). -------------------------------------------------------------------------------- [color=940306]MySQL Data Types[/color]
    Below is the different MySQL data types that can be used:

    i

    [color=FA0309]Primary Keys and Auto Increment Fields[/color]
    Each table should have a primary key field. A primary key is used to uniquely identify the rows in a table. Each primary key value must be unique within the table. Furthermore, the primary key field cannot be null because the database engine requires a value to locate the record. The primary key field is always indexed. There is no exception to this rule! You must index the primary key field so the database engine can quickly locate rows based on the key's value. The following example sets the personID field as the primary key field. The primary key field is often an ID number, and is often used with the AUTO_INCREMENT setting. AUTO_INCREMENT automatically increases the value of the field by 1 each time a new record is added. To ensure that the primary key field cannot be null, we must add the NOT NULL setting to the field. [color=FA0309]Example[/color]
    $sql = "CREATE TABLE person
    (
    personID int NOT NULL AUTO_INCREMENT,
    PRIMARY KEY(personID),
    FirstName varchar(15),
    LastName varchar(15),
    Age int
    )";
    mysql_query($sql,$con);
    كن أول من يقيم الموضوع
    12345