sql - Create 语句中的变量

Question

我正在尝试在数据库设置的创建脚本中使用一些变量。我不确定如何使用它们。请解释如何正确格式化我的代码。下面是我尝试的代码，以及我得到的错误:

SET @username = 'xxxx'; -- store number goes here
SET @password = 'xxxxxx'; -- store password goes here

CREATE TABLE IF NOT EXISTS `my_table` (
`id` int(11) auto_increment,
`release_date` datetime,
`front_image_file` varchar(255),
PRIMARY KEY  (`id`)
) ENGINE=FEDERATED  
DEFAULT CHARSET=latin1 
AUTO_INCREMENT=1 
CONNECTION='mysql://`@username`:`@password`@host_name:3306/database_name/table_tame' ;

错误

#1432 - Can't create federated table. The data source connection string 'mysql://`@username`:`@password`@host_name:3306/databa' is not in the correct format

我也试过没有 `

尝试 EdmundG 的解决方案

SET @username = 'xxxx'; -- store number goes here
SET @password = 'xxxxxx'; -- store password goes here

CREATE TABLE IF NOT EXISTS `my_table` (
`id` int(11) auto_increment,
`release_date` datetime,
`front_image_file` varchar(255),
PRIMARY KEY  (`id`)
) ENGINE=FEDERATED  
DEFAULT CHARSET=latin1 
AUTO_INCREMENT=1 
CONNECTION='Uid=@username; Pwd=@password; Server=****; Port=3306; Database =****; Table=****;' ;

没用，还是说格式不正确

Answer 1

MySQL 不支持直接将变量插值到这样的语法中。

但是，您可以使用这些变量构建一个字符串，然后准备并执行它作为 dynamic SQL .

SET @username = 'xxxx'; -- store number goes here
SET @password = 'xxxxxx'; -- store password goes here

SET @sql = CONCAT('CREATE TABLE IF NOT EXISTS `my_table` (',
    '  `id` int(11) auto_increment,',
    '  `release_date` datetime,',
    '  `front_image_file` varchar(255),',
    '  PRIMARY KEY  (`id`)',
    ') ENGINE=FEDERATED',
    ' DEFAULT CHARSET=latin1', 
    ' AUTO_INCREMENT=1', 
    ' CONNECTION=''mysql://', @username, ':', @password, 
    '@host_name:3306/database_name/table_tame');

PREPARE stmt FROM @sql;

EXECUTE stmt;

DEALLOCATE PREPARE stmt;