Php 如果您的标题字段可以为空，那么使用book.isbn13也会更安全。我刚才也尝试过，因为有些标题是空的。在我看来是个赢家。我确实需要在I.isbn13=book.isbn13上添加一个左连接书，仅供参考。再次感谢您的帮助。很抱歉在测试您的示例时出现延迟，但

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如果您的标题字段可以为空，那么使用book.isbn13也会更安全。我刚才也尝试过，因为有些标题是空的。在我看来是个赢家。我确实需要在I.isbn13=book.isbn13上添加一个左连接书，仅供参考。再次感谢您的帮助。很抱歉在测试您的示例时出现延迟，但是当我运行它时，我在上看到一个sql语法错误，即“cnt”。我不确定这本书是什么。意思是说，你能解释一下吗？这样我就可以更正错误并重试代码了？。Thanksbook是book表，我仍然想知道为什么会出现语法错误，stll检查…我做了一些更改，并将book.*更改为book.title，它似乎可以工作。我仍然需要验证数学，但乍一看似乎很接近。谢谢你的帮助。好的，很酷，我只是想弄明白，如果你的标题字段可以为空，那么使用book.isbn13也会更安全。我刚才也试过了，因为有些标题是空的。在我看来是个赢家。我确实需要在I.isbn13=book.isbn13上添加一个左连接书，仅供参考。再次感谢你的帮助。

SELECT sku, quantity, inventory.isbn13, author, title, pub_date, binding, 
      defect.defect, source, location from inventory
      LEFT JOIN location ON inventory.location_id = location.location_id
      LEFT JOIN source ON inventory.source_id = source.source_id
      LEFT JOIN book ON inventory.isbn13 = book.isbn13
      LEFT JOIN defect ON inventory.defect_id = defect.defect_id
      LEFT JOIN book_condition ON book_condition.condition_id = defect.condition_id
      WHERE quantity > '0' and location.location_id >= '986' and location.location_id <= '989'
      ORDER BY inventory.location_id, sku

foreach ($results as $row) {
    $location_count [$row['location_id']]++;
}
echo $location_count [986]; // outputs 17

SELECT count(*), sku, quantity, inventory.isbn13, author, title, pub_date, binding, 
      defect.defect, source, location from inventory
      LEFT JOIN location ON inventory.location_id = location.location_id
      LEFT JOIN source ON inventory.source_id = source.source_id
      LEFT JOIN book ON inventory.isbn13 = book.isbn13
      LEFT JOIN defect ON inventory.defect_id = defect.defect_id
      LEFT JOIN book_condition ON book_condition.condition_id = defect.condition_id
      WHERE quantity > '0' and location.location_id >= '986' and location.location_id <= '989'
      ORDER BY inventory.location_id, sku
      GROUP BY location.location_id

mysql> select * from actor where actor_id>190;
+----------+------------+-------------+---------------------+
| actor_id | first_name | last_name   | last_update         |
+----------+------------+-------------+---------------------+
|      191 | GREGORY    | GOODING     | 2012-05-22 15:12:26 |
|      192 | JOHN       | SUVARI      | 2012-05-22 15:12:26 |
|      193 | BURT       | TEMPLE      | 2012-05-22 15:12:26 |
|      194 | MERYL      | ALLEN       | 2012-05-22 15:12:26 |
|      195 | JAYNE      | SILVERSTONE | 2012-05-22 15:12:26 |
|      196 | BELA       | WALKEN      | 2012-05-22 15:12:26 |
|      197 | REESE      | WEST        | 2012-05-22 15:12:26 |
|      198 | MARY       | KEITEL      | 2012-05-22 15:12:26 |
|      199 | JULIA      | FAWCETT     | 2012-05-22 15:12:26 |
|      200 | THORA      | TEMPLE      | 2012-05-22 15:12:26 |
|      205 | 1          | 2           | 0000-00-00 00:00:00 |
|      206 | a          | b           | 0000-00-00 00:00:00 |
+----------+------------+-------------+---------------------+
12 rows in set (0.00 sec)

mysql> select FOUND_ROWS();
+--------------+
| FOUND_ROWS() |
+--------------+
|           12 |
+--------------+
1 row in set (0.00 sec)

SELECT
    sku, 
    quantity, 
    inventory.isbn13, 
    author, 
    title, 
    pub_date, 
    binding, 
    defect.defect, 
    source, 
    location,
    t.cnt
FROM 
    inventory i
        INNER JOIN 
            (
            SELECT
                inventory.location_id,
                COUNT(book.isbn13) as `cnt`
            FROM inventory
                  LEFT JOIN book ON inventory.isbn13 = book.isbn13
            GROUP BY inventory.location_id
            ) t ON t.location_id = i.location_id
        INNER JOIN location l       ON i.location_id = l.location_id
        LEFT JOIN source            ON i.source_id = source.source_id
        LEFT JOIN defect            ON i.defect_id = defect.defect_id
        LEFT JOIN book_condition    ON book_condition.condition_id = defect.condition_id
WHERE 
    i.quantity > '0' 
AND l.location_id >= '986' 
AND l.location_id <= '989'