MySQL的 - 如何编写SELECT语句中正确

Question

我有全文搜索，并在WHERE状态正常的搜索和额外的JOIN这样

SELECT 
customer.*, 
countries.name as country 
FROM customer 
LEFT JOIN countries ON countries.ID = customer.country_id 
WHERE customer.num = :keyword 
    OR customer.city = :keyword 
    OR customer.email = :keyword 
    OR MATCH (customer.company) AGAINST (:keyword) 
    OR countries.name = :keyword 

查询与全文检索的组合一个MySQL SELECT声明成(customer.company)柱只要TABLE.COLUMN countries.name是的WHERE条件部分返回no result。但是询问countries.name本身是成功的。

如何正确编写的SELECT语句返回使用从上面的例子所有WHERE组件的组合成功的查询？

编辑：

在以前的版本我用这个statment

SELECT 
    customer.* , 
    countries.name 
    FROM customer, countries 
    WHERE customer.country_id=countries.ID 
    AND MATCH (customer.company) AGAINST (:keyword) 

    UNION 

    SELECT 
    customer.*, 
    countries.name 
    FROM customer, countries 
    WHERE customer.country_id=countries.ID 
    AND countries.name=:keyword 

效果很好。我只是不知道这是否是使用不同搜索（全文和普通）查询两个表的有效方式。另外，当我搜索超过2列时，代码很容易被炸毁，这是我想避免的。

任何更多的想法和帮助是值得欢迎

Answer 1

您应该检查NULLs，因为你使用的是LEFT JOIN：

SELECT 
    customer.*, 
    countries.name as country 
FROM customer 
LEFT JOIN countries ON countries.ID = customer.country_id 
WHERE customer.num = :keyword 
    OR customer.city = :keyword 
    OR customer.email = :keyword 
    OR MATCH (customer.company) AGAINST (:keyword) 
    OR (countries.name = :keyword OR countries.name IS NULL) 

只是为了澄清，在LEFT JOIN的右表的条件，应只放在在ON条款，而不是WHERE子句中。这是一个有点不同，因为要比较它与所有其他条件，因此 - 在NULL比较。

Answer 2

我的解决办法是刚刚设置的默认值= ''到countries.name使用CASE WHEN

(CASE WHEN countries.name is null then 'default value' else countries.name END) 

新的查询

SELECT 
customer.*, 
countries.name as country 
FROM customer 
LEFT JOIN countries ON countries.ID = customer.country_id 
WHERE customer.num = :keyword 
    OR customer.city = :keyword 
    OR customer.email = :keyword 
    OR MATCH (customer.company) AGAINST (:keyword) 
    OR (CASE WHEN countries.name is null then '' else countries.name END) = :keyword