MySQL脚本问题

Question

脚本创建 sql 命令以将表从一个数据库复制到另一个数据库，前提是该表在目标数据库中不存在。该查询检查该表是否在 sakila1 中不存在并且它存在于 sakila 中，则应创建表。

当在 mysql 命令提示符下运行时，下面的查询

SELECT concat('CREATE TABLE if does not exists sakila1.', TABLE_NAME, ' like sakila.', TABLE_NAME, ';') 
FROM information_schema.`TABLES` 
WHERE TABLE_SCHEMA = 'sakila'

它只是写了下面的sql命令

CREATE TABLE if does not exists sakila1.actor like sakila.actor;                      |

| CREATE TABLE if does not exists sakila1.actor_info like sakila.actor_info;                 |

| CREATE TABLE if does not exists sakila1.address like sakila.address;                    |

| CREATE TABLE if does not exists sakila1.category like sakila.category;                   |

| CREATE TABLE if does not exists sakila1.city like sakila.city;                       |

| CREATE TABLE if does not exists sakila1.country like sakila.country;                    |

| CREATE TABLE if does not exists sakila1.customer like sakila.customer;                   |

| CREATE TABLE if does not exists sakila1.customer_list like sakila.customer_list;              |

| CREATE TABLE if does not exists sakila1.film like sakila.film;                       |

| CREATE TABLE if does not exists sakila1.film_actor like sakila.film_actor;                 |

| CREATE TABLE if does not exists sakila1.film_category like sakila.film_category;              |

| CREATE TABLE if does not exists sakila1.film_list like sakila.film_list;                  |

| CREATE TABLE if does not exists sakila1.film_text like sakila.film_text;                  |

| CREATE TABLE if does not exists sakila1.inventory like sakila.inventory;                  |

| CREATE TABLE if does not exists sakila1.language like sakila.language;                   |

| CREATE TABLE if does not exists sakila1.nicer_but_slower_film_list like sakila.nicer_but_slower_film_list; |

| CREATE TABLE if does not exists sakila1.payment like sakila.payment;                    |

| CREATE TABLE if does not exists sakila1.rental like sakila.rental;                     |

| CREATE TABLE if does not exists sakila1.sales_by_film_category like sakila.sales_by_film_category;     |

| CREATE TABLE if does not exists sakila1.sales_by_store like sakila.sales_by_store;             |

| CREATE TABLE if does not exists sakila1.staff like sakila.staff;                      |

| CREATE TABLE if does not exists sakila1.staff_list like sakila.staff_list;                 |

| CREATE TABLE if does not exists sakila1.store like sakila.store;                      |

+------------------------------------------------------------------------------------------------------------+

23 rows in set (0.00 sec)

SQL 命令不会被执行，而只是显示为 sql 命令。

我需要通过运行上述查询在 sakila1 中创建所需的表，而不是仅仅编写创建表的命令。

谁能帮帮我！

标志

Answer 1

CREATE FUNCTION fn_table_exists(dbName VARCHAR(255), tableName VARCHAR(255))
  RETURNS BOOLEAN
  BEGIN
    DECLARE totalTablesCount INT DEFAULT (
      SELECT COUNT(*)
      FROM information_schema.TABLES
      WHERE (TABLE_SCHEMA COLLATE utf8_general_ci = dbName COLLATE utf8_general_ci)
        AND (TABLE_NAME COLLATE utf8_general_ci = tableName COLLATE utf8_general_ci)
    );
    RETURN IF(
      totalTablesCount > 0,
      TRUE,
      FALSE
    );
END
;


Set @query:=''
SELECT @query:=@query+concat('IF fn_table_exists(sakila1,',TABLE_NAME,')=FALSE THEN CREATE TABLE sakila1.', TABLE_NAME, ';') FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'sakila'
PREPARE stmt FROM @query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;