我怎麼使用CREATE DATABASE語句

Question

一個變量我有這樣的過程：

DELIMITER // 

create DEFINER = 'root'@'localhost' procedure create_db(name TEXT) 
BEGIN 
DECLARE temp TEXT; 
DECLARE user TEXT; 
SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = name INTO temp; 
    if temp = name then 
     SIGNAL SQLSTATE '45002' SET MESSAGE_TEXT = 'This database already exist'; 
    else 
     SELECT USER() INTO user; 
     create database name; 
     grant all privileges on name.* to user with grant option; 
    END IF; 
END // 

DELIMITER ; 

它的偉大隻是它提供字面意思是「名」，而不是變量名的工程價值。我怎麼知道這個名字是一個變量？在php或者類似的$ name中。我瀏覽了許多文檔，但他們都使用無前綴的變量。

Answer 1

你只需要使用準備好的語句，這裏是工作代碼：

DELIMITER // 

drop procedure if exists create_db // 

create procedure create_db(name TEXT) 
BEGIN 
    DECLARE temp TEXT; 
    DECLARE user TEXT; 
    SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = name INTO temp; 
    if temp = name then 
    SIGNAL SQLSTATE '45002' SET MESSAGE_TEXT = 'This database already exist'; 
    else 
    SELECT USER() INTO user; 

    SET @s = CONCAT('CREATE DATABASE ', name); 
    PREPARE stmt_create FROM @s; 
    EXECUTE stmt_create; 
    DEALLOCATE PREPARE stmt_create; 

    SET @s = CONCAT('GRANT ALL PRIVILEGES ON ', name, '.* TO ', user, ' WITH GRANT OPTION'); 
    PREPARE stmt_grant FROM @s; 
    EXECUTE stmt_grant; 
    DEALLOCATE PREPARE stmt_grant; 

    END IF; 
END // 

DELIMITER ;