Create语句中的变量

Question

我试图在创建脚本中使用一些变量来进行数据库设置.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=****;' ;

没有用,仍然说格式不正确

Answer 1

MySQL不支持将变量插值直接转换为这样的语法.

但是,您可以使用这些变量构建一个字符串,然后准备并将其作为动态SQL执行.

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 stmt;