How can those two SQL statements be combined into

问题:

I wrote and would like to combine these 2 sql, one is based on results of another. I checked this post, but looks like its not results based. How could I achieve it ?

First sql:

SELECT
    `potential`.*,
    `customer`.`ID` as 'FID_customer'
FROM
    `os_potential` as `potential`,
    `os_customer` as `customer`
WHERE `potential`.`FID_author` = :randomID
      AND `potential`.`converted` = 1
      AND `potential`.`street` = `customer`.`street`
      AND `potential`.`zip` = `customer`.`zip`
      AND `potential`.`city` = `customer`.`city`;

Second sql:

SELECT
    sum(`order`.`price_customer`) as 'Summe'
FROM
    `os_order` as `order`,
    `RESUTS_FROM_PREVIOUS_SQL_STATEMENT` as `results`
WHERE `order`.`FID_status` = 10
      AND `results`.`FID_customer` = `order`.`FID_customer`;

I would like to get everything from first sql + the 'Summe' from second sql.

TABLES

1.Potentials:

+----+------------+-----------+--------+-----+------+
| ID | FID_author | converted | street | zip | city |
+----+------------+-----------+--------+-----+------+

2.Customers:

+----+--------+-----+------+
| ID | street | zip | city |
+----+--------+-----+------+

3.Orders:

+----+--------------+----------------+
| ID | FID_customer | price_customer |
+----+--------------+----------------+

回答1:

SELECT p.*
     , c.ID FID_customer
     , o.summe
  FROM os_potential p
  JOIN os_customer c
    ON c.street = p.street 
   AND c.zip = p.zip 
   AND c.city = p.city 
  JOIN 
     ( SELECT FID_customer
            , SUM(price_customer) Summe
         FROM os_order 
        WHERE FID_status = 10
        GROUP
           BY FID_customer
     ) o
    ON o.FID_customer = c.ID
 WHERE p.FID_author = :randomID 
   AND p.converted = 1
   ;

回答2:

You would just write a single query like this:

SELECT sum(o.price_customer) as Summe
FROM os_order o JOIN
     os_potential p JOIN
     os_customer c
     ON p.street = c.street AND p.zip = c.zip AND p.city = c.city JOIN
     os_order o2
     ON o2.FID_customer = c.FID_customer
WHERE p.FID_author = :randomID AND p.converted = 1 AND
      o2.FID_status = 10 ;

Notes:

• Never use commas in the FROM clause. Always use explicit JOIN syntax with conditions in an ON clause.
• Table aliases are easier to follow when they are short. Abbreviations for the table names is commonly used.
• Backticks are only necessary when the table/column name needs to be escaped. Yours don't need to be escaped.

回答3:

If the 1st query return 1 record per customer, then just simply join the 3 tables, keep the sum and use the group by clause:

SELECT
    `potential`.*,
    `customer`.`ID` as 'FID_customer',
    sum(`order`.`price_customer`) as Summe
FROM
    `os_potential` as `potential`
INNER JOIN
    `os_customer` as `customer`
ON  `potential`.`street` = `customer`.`street`
      AND `potential`.`zip` = `customer`.`zip`
      AND `potential`.`city` = `customer`.`city`
LEFT JOIN
    `os_order` as `order`
ON  `results`.`FID_customer` = `order`.`FID_customer`
      AND `order`.`FID_status` = 10
WHERE `potential`.`FID_author` = :randomID
      AND `potential`.`converted` = 1
GROUP BY `customer`.`ID`, <list all fields from potential table>

If the 1st query may return multiple records per customer, then you need to do the summing in a subquery:

SELECT
    `potential`.*,
    `customer`.`ID` as 'FID_customer',
    `order`.Summe
FROM
    `os_potential` as `potential`
INNER JOIN
    `os_customer` as `customer`
ON  `potential`.`street` = `customer`.`street`
      AND `potential`.`zip` = `customer`.`zip`
      AND `potential`.`city` = `customer`.`city`
LEFT JOIN
    (SELECT FID_customer, sum(price_customer) as Summe
     FROM `os_order`
     WHERE FID_status=10 
     GROUP BY FID_customer
    ) as `order`
ON  `results`.`FID_customer` = `order`.`FID_customer`
WHERE `potential`.`FID_author` = :randomID
      AND `potential`.`converted` = 1

回答4:

I think you should use a subselect, but be careful with the number of results, it's not the best for performance.

You can do something like this:

SELECT n1, n2, (select count(1) from whatever_table) as n3, n4 from whatever_table 

note that the subselect must return just 1 result, in other case you'll have an error