Create MySQL Tables ~ Java Tutorials by Experts

Friday, October 31, 2014

Create MySQL Tables

The table creation command requires:

Name of the table
Names of fields
Definitions for each field

Syntax:

Here is generic SQL syntax to create a MySQL table:

CREATE TABLE table_name (column_name column_type);

Now, we will create following table in JAVATUTORIALS database.

javatutorials_tbl(
   javatutorial_id INT NOT NULL AUTO_INCREMENT,
   javatutorial_title VARCHAR(100) NOT NULL,
   javatutorial_author VARCHAR(40) NOT NULL,
   submission_date DATE,
   PRIMARY KEY ( tutorial_id )
);

Here few items need explanation:

Field Attribute NOT NULL is being used because we do not want this field to be NULL. So if user will try to create a record with NULL value, then MySQL will raise an error.
Field Attribute AUTO_INCREMENT tells MySQL to go ahead and add the next available number to the id field.
Keyword PRIMARY KEY is used to define a column as primary key. You can use multiple columns separated by comma to define a primary key.

Creating Tables from Command Prompt:

This is easy to create a MySQL table from mysql> prompt. You will use SQL command CREATE TABLE to create a table.

Example:

Here is an example, which creates javatutorials_tbl:

root@host# mysql -u root -p
Enter password:*******
mysql> use JAVATUTORIALS;
Database changed
mysql> CREATE TABLE javatutorials_tbl(
   -> tutorial_id INT NOT NULL AUTO_INCREMENT,
   -> tutorial_title VARCHAR(100) NOT NULL,
   -> tutorial_author VARCHAR(40) NOT NULL,
   -> submission_date DATE,
   -> PRIMARY KEY ( tutorial_id )
   -> );
Query OK, 0 rows affected (0.16 sec)
mysql>

NOTE: MySQL does not terminate a command until you give a semicolon (;) at the end of SQL command.

Creating Tables Using PHP Script:

To create new table in any existing database you would need to use PHP function mysql_query(). You will pass its second argument with proper SQL command to create a table.

Example:

Here is an example to create a table using PHP script:

<html>
<head>
<title>Creating MySQL Tables</title>
</head>
<body>
<?php
$dbhost = 'localhost:3036';
$dbuser = 'root';
$dbpass = 'rootpassword';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
  die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully<br />';
$sql = "CREATE TABLE javatutorials_tbl( ".
       "javatutorial_id INT NOT NULL AUTO_INCREMENT, ".
       "javatutorial_title VARCHAR(100) NOT NULL, ".
       "javatutorial_author VARCHAR(40) NOT NULL, ".
       "submission_date DATE, ".
       "PRIMARY KEY ( tutorial_id )); ";
mysql_select_db( 'JAVATUTORIALS' );
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
  die('Could not create table: ' . mysql_error());
}
echo "Table created successfully\n";
mysql_close($conn);
?>
</body>
</html>

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Java Tutorials by Experts

Friday, October 31, 2014