Question

我有2个具有以下结构的表：

Custom Pricing List
+------------+--------------+------------ +
| stock_code | stored_price | pricing_ref | 
+------------+--------------+------------ +

Generic Pricing List
+------------+---------------------+--------------+-------------+--------------+
| stock_code | last_purchase_price | sales_price  | description | qty_in_stock |
+------------+---------------------+--------------+-------------+--------------+

我想要返回的内容如下：

+------------+---------------------+--------------+--------------+-------------+
| stock_code | last_purchase_price | sales_price  | description | qty_in_stock |
+------------+---------------------+--------------+--------------+-------------+

目前我只使用以下MySQL语句查询最后一个表：

SELECT * FROM $table WHERE $column LIKE '%$term%' $or LIMIT 0,10

但是，我想合并2，仍然可以在stock_code列上进行通配符搜索。

所有结果必须返回description和qty_in_stock。结果中的sales_price将来自stored_price的{{1}}或来自Custom Pricing Table的{{1}}，但sales_price优先于Generic Pricing Table来自stored_price。

我知道我需要进行UNION查询，但我不确定如何编写它。

修改

使用声明：

sales_price

我现在收到以下错误：

Generic Pricing Table

Answer 1

我认为你可以加入这两个表格。试试这个：

SELECT 
generic.stock_code, 
generic.last_purchase_price, 
IFNULL(custom.stored_price, generic.sales_price) AS actual_price, 
generic.description, 
generic.qty_in_stock 
FROM 
Generic_Pricing_List generic
JOIN Custom_Pricing_List custom
on custom.stock_code = generic.stock_code
WHERE $column LIKE '%$term%' $or LIMIT 0,10;

如果stored_price不为null且已定义，则会将其拾取。否则，将收取sales_price。

Answer 2

SELECT t1.*, t2.field1, t2.field2 
FROM $table1 AS t1
LEFT JOIN $table2 AS t2 ON (t1.stock_code = t2.stock_code) 
WHERE t1.$column LIKE '%$term%' $or 
LIMIT 0,10

只需使用JOIN

即可

Answer 3

1.42857143将为您提供font-size的所有行以及来自Left Inner Join的匹配行。

Generic_Pricing_List

Answer 4

SELECT g.*
FROM Generic_Pricing_List g
LEFT JOIN Custom_Pricing_List c
    ON g.stock_code = c.stock_code
WHERE g.Search_Column LIKE '%Term%'
LIMIT 0,10

Answer 5

您可以使用联盟，但不是必需的。但是，对于较大的数据集，联合可能更有效，因为＆＃34;如果＆＃34; s可能很昂贵。又快又脏：

SELECT gpl.stock_code, last_purchase_price, if(stored_price is null, sales_price, stored_price) as sales_price, description, qty_in_stock
FROM Generic_Pricing_List gpl
LEFT JOIN Custom_Pricing_List cpl
    ON gpl.stock_code = cpl.stock_code
    AND cpl.stored_price != ''
    AND cpl.stored_price IS NOT NULL
WHERE $column LIKE '%$term%' $or
LIMIT 0,10

使用联盟：

SELECT * FROM 
(SELECT gpl.stock_code, last_purchase_price, stored_price as sales_price, description, qty_in_stock
FROM Generic_Pricing_List gpl
JOIN Custom_Pricing_List cpl
    ON gpl.stock_code = cpl.stock_code
    AND cpl.stored_price != ''
    AND cpl.stored_price IS NOT NULL
WHERE $column LIKE '%$term%' $or
UNION
SELECT gpl.stock_code, last_purchase_price, sales_price, description, qty_in_stock
FROM Generic_Pricing_List gpl
WHERE $column LIKE '%$term%' $or) foo
GROUP BY foo.stock_code
LIMIT 0,10

小心＆＃34;或＆＃34;注入语句，因为它可能会导致结果出现问题。

合并2个MySQL表

修改

5 个答案: