Mariadb 简明教程

MariaDB - Create Tables

在本教程中，我们将学习如何创建表。在创建表之前，首先要确定其名称、字段名和字段定义。

In this chapter, we will learn how to create tables. Before creating a table, first determine its name, field names, and field definitions.

以下是一般创建表语法：

Following is the general syntax for table creation −

CREATE TABLE table_name (column_name column_type);

查看用于在 PRODUCTS 数据库中创建表的命令：

Review the command applied to creating a table in the PRODUCTS database −

databaseproducts_ tbl(
   product_id INT NOT NULL AUTO_INCREMENT,
   product_name VARCHAR(100) NOT NULL,
   product_manufacturer VARCHAR(40) NOT NULL,
   submission_date DATE,
   PRIMARY KEY ( product_id )
);

上述示例使用“NOT NULL”作为字段属性，以避免因空值引起的错误。属性“AUTO_INCREMENT”指示 MariaDB 将下一个可用值添加到 ID 字段。关键字 primary key 定义列为 primary key 。多个以逗号分隔的列可以定义一个主键。

The above example uses “NOT NULL” as a field attribute to avoid errors caused by a null value. The attribute “AUTO_INCREMENT” instructs MariaDB to add the next available value to the ID field. The keyword primary key defines a column as the primary key. Multiple columns separated by commas can define a primary key.

创建表的两种主要方法是使用命令提示符和 PHP 脚本。

The two main methods for creating tables are using the command prompt and a PHP script.

The Command Prompt

使用 CREATE TABLE 命令执行任务，如下所示：

Utilize the CREATE TABLE command to perform the task as shown below −

root@host# mysql -u root -p
Enter password:*******
mysql> use PRODUCTS;
Database changed
mysql> CREATE TABLE products_tbl(
   -> product_id INT NOT NULL AUTO_INCREMENT,
   -> product_name VARCHAR(100) NOT NULL,
   -> product_manufacturer VARCHAR(40) NOT NULL,
   -> submission_date DATE,
   -> PRIMARY KEY ( product_id )
   -> );
mysql> SHOW TABLES;
+------------------------+
| PRODUCTS               |
+------------------------+
| products_tbl           |
+------------------------+

确保用分号终止所有命令。

Ensure all commands are terminated with a semicolon.

PHP Create Table Script

PHP 提供了 mysql_query() 用于创建表。其第二个参数包含必要的 SQL 命令 −

PHP provides mysql_query() for table creation. Its second argument contains the necessary SQL command −

<html>
   <head>
      <title>Create a MariaDB Table</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 products_tbl( ".
            "product_id INT NOT NULL AUTO_INCREMENT, ".
            "product_name VARCHAR(100) NOT NULL, ".
            "product_manufacturer VARCHAR(40) NOT NULL, ".
            "submission_date DATE, ".
            "PRIMARY KEY ( product_id )); ";

         mysql_select_db( 'PRODUCTS' );
         $retval = mysql_query( $sql, $conn );

         if(! $retval ) {
            die('Could not create table: ' . mysql_error());
         }
         echo "Table created successfully\n";

         mysql_close($conn);
      ?>
   </body>
</html>

成功创建表后，您将看到以下输出 −

On successful table creation, you will see the following output −

mysql> Table created successfully