如何使用where條件聯接兩個表並顯示記錄

Question

所以我很難在Stack上找到一個好的答案。 我正在尋找一個查詢，將兩個表上的信息結合在一起。 到目前為止，這就是我所擁有的。 實際情況如下：

為了實現這一點，我將嘗試從我的角度進行更多說明：

我有兩個表：

Comparitive_st_sup
___________________

id  | tender_id | item_name | slno | supplier_name | prod_description
________________________________________________________________________

1       401        Collinear   1      OnlineMetals    Description comes here    
2       401        Filter      2      OnlineMetals    Description comes here
3       401        Antenna     3      OnlineMetals    Description Comes here
4       455        Primer      1      KR Electronics  Description comes here
5       455        Chock       2      KR Electronics  Description comes here


comparitive_st_tech_compliance
_______________________________

id | tender_id | item_name  | slno | supplier_name  | tech_analyst_comment
__________________________________________________________________________

1      401        Collinear    1      OnlineMetals     90%
2      401        Filter       2      OnlineMetals     25%
3      401        Antenna      3      OnlineMetals     87%
4      455        Primer       1      KR Electronics   64%
5      455        Chick        2      KR Electronics   80%

Now i am expecting a result like:

401    Collinear     1    OnlineMetals    Description comes here   90%
401    Filter        2    OnlineMetals    Description comes here   25%
401    Antenna       3    OnlineMetals    Description comes here   87%

根據所選的bidd_id，該值將作為查詢字符串傳遞，並且必須相應地顯示記錄。 幫助表示贊賞。

我試過了，但是結果不正確：

 Select comparitive_st_sup.*,
  comparitive_st_sup.tender_id As tender_id1,
  comparitive_st_sup.supplier_name As supplier_name1,
  comparitive_st_sup.slno As slno1,
  comparitive_st_sup.prod_description As prod_description1,
  comparitive_st_sup.item_name As item_name1,
  comparitive_st_sup.total As total1,
  comparitive_st_tech_compliance.tech_analyst_comment
  From comparitive_st_tech_compliance
  Right Join comparitive_st_sup On comparitive_st_sup.tender_id =
  comparitive_st_tech_compliance.tender_id
  Where comparitive_st_sup.tender_id = 401     

我需要顯示來自comparitive_st_sup的所有字段，並且僅顯示一個條件條件為bid_id的字段（tech_analyst_comment）。 現在，記錄正在重復。 而不是顯示3條記錄，而是顯示9條記錄。 我有什么錯誤嗎？

Answer 1

從您的評論中，我相信comparitive_st_tech_compliance相對於comparitive_st_sup表中的一行，具有更多的一行，而單個的bid_id。 如果是這樣，那么它將返回多行與您使用哪個Join無關。

Answer 2

您可能需要在這里這樣做：

Select comparitive_st_sup.*,
  comparitive_st_sup.tender_id As tender_id1,
  comparitive_st_sup.supplier_name As supplier_name1,
  comparitive_st_sup.slno As slno1,
  comparitive_st_sup.prod_description As prod_description1,
  comparitive_st_sup.item_name As item_name1,
  comparitive_st_sup.total As total1,
  comparitive_st_tech_compliance.tech_analyst_comment
  From comparitive_st_tech_compliance
  Where comparitive_st_sup.tender_id = 401  AND comparitive_st_tech_compliance.tender_id =  tender_id1

Answer 3

SELECT comparitive_st_sup.*,
  comparitive_st_sup.tender_id As tender_id1,
  comparitive_st_sup.supplier_name As supplier_name1,
  comparitive_st_sup.slno As slno1,
  comparitive_st_sup.prod_description As prod_description1,
  comparitive_st_sup.item_name As item_name1,
  comparitive_st_sup.total As total1,
  comparitive_st_tech_compliance.tech_analyst_comment
  FROM comparitive_st_sup, comparitive_st_tech_compliance
  WHERE comparitive_st_sup.tender_id = 401
  AND comparitive_st_tech_compliance.tender_id = comparitive_st_sup.tender_id
  GROUP BY comparitive_st_sup.tender_id;

Answer 4

如果您不希望或不能使用GROUP BY ，則可以嘗試子查詢。 您還可以ORDER BY的子查詢日期/ ID。

SELECT
    cs.*,
    cs.tender_id AS tender_id1,
    cs.supplier_name AS supplier_name1,
    cs.slno AS slno1,
    cs.prod_description AS prod_description1,
    cs.item_name AS item_name1,
    cs.total AS total1,
    (
        SELECT
            ct.tech_analyst_comment
        FROM comparitive_st_tech_compliance AS ct
        WHERE ct.tender_id = cs.tender_id
        LIMIT 1
    ) AS tech_analyst_comment
FROM comparitive_st_sup AS cs
WHERE cs.tender_id = 401

---

LE： IF和IF slno在兩個表中都是相同的標識符（ comparitive_st_sup.slno = comparitive_st_tech_compliance.slno ），因此您可以使用AND comparitive_st_sup.slno = comparitive_st_tech_compliance.slno的額外連接參數將它們加入，因此您的初始查詢將看起來像這樣：

Select comparitive_st_sup.*,
  comparitive_st_sup.tender_id As tender_id1,
  comparitive_st_sup.supplier_name As supplier_name1,
  comparitive_st_sup.slno As slno1,
  comparitive_st_sup.prod_description As prod_description1,
  comparitive_st_sup.item_name As item_name1,
  comparitive_st_sup.total As total1,
  comparitive_st_tech_compliance.tech_analyst_comment
From comparitive_st_tech_compliance
Right Join comparitive_st_sup On
    comparitive_st_sup.tender_id = comparitive_st_tech_compliance.tender_id AND
    comparitive_st_sup.slno = comparitive_st_tech_compliance.slno
Where comparitive_st_sup.tender_id = 401

但是如果表* _st_sup和* _tech_compliance中的slno不同，則您將需要在bid_id旁邊的產品和注釋之間添加關系

comparitive_st_tech_compliance
+-----------------------------------------------------------------------------------------+
| id | tender_id | product_id | item_name  | slno | supplier_name  | tech_analyst_comment |
+-----------------------------------------------------------------------------------------+
|  1 | 401       |     1      | Collinear  |   1  | OnlineMetals   | description          |
+-----------------------------------------------------------------------------------------+

其中comparitive_st_tech_compliance.product_id是Comparitive_st_sup.id，這也使我到了建議您更改數據庫架構（結構）的地步

旁注：因此，從您的數據庫結構中，需要指出的一件事是，它的設計不佳。 兩個表格中都有重復的字段，因此如果需要更新ex。 供貨商名稱，您將需要更新所有表。 現在假設您願意進行更改，我建議將數據分成3個表，而不考慮slno可能是2個表之間的標識符。

comparative_supplier
+---------------------+
| id | supplier_name  |
+---------------------+
| 1  | OnlineMetals   |
| 2  | KR Electronics |
+---------------------+

comparitive_st_sup
+--------------------------------------------------------------------+
| id | tender_id | supplier_id | slno | item_name | prod_description |
+--------------------------------------------------------------------+
| 1  | 401       |      1      |   1  | Collinear | description      |
| 2  | 401       |      1      |   2  | Filter    | description      |
| 3  | 401       |      1      |   3  | Antenna   | description      |
| 4  | 455       |      2      |   1  | Primer    | description      |
| 5  | 455       |      2      |   2  | Chock     | description      |
+--------------------------------------------------------------------+

comparitive_st_tech_compliance
+-----------------------------------------+
| id   | id_supply | tech_analyst_comment |
+-----------------------------------------+
| 15   |     1     |         90%          |
| 56   |     2     |         25%          |
| 123  |     3     |         87%          |
| 412  |     4     |         64%          |
| 684  |     5     |         80%          |
+-----------------------------------------+

使用這種表結構，您可以輕松地連接表而無需重復輸入，並且無需更改所有表即可更改字段。

SELECT
    cs.tender_id, sn.supplier_name, cs.slno, cs.item_name,
    cs.prod_description, ct.tech_analyst_comment
FROM comparitive_st_sup AS cs
LEFT JOIN comparative_supplier AS sn ON sn.id = cs.supplier_id
LEFT JOIN comparitive_st_tech_compliance AS ct ON ct.id_supply = cs.id
WHERE cs.tender_id = 401

或僅更改st_sup表並包含技術注釋，因為這兩個表僅在技術注釋和產品描述上有所不同