如何在MySQL中用連接表連接兩列

Question

我有兩個表issue_details和payees ，如下所示，帶有值：

表格： issue_details

+----------+------------+----------+----------+
| check_no | issue_date | payee_id | lddap_no | 
+----------+------------+----------+----------+
|        0 | 2015-01-01 |          | 11101-15 | 
|        1 | 2015-01-24 |          | 11101-15 |
|    34561 | 2015-01-24 | 10       |          |
|    34562 | 2015-01-24 | 13       |          | 
+----------+------------+----------+----------+

表： 收款人

+----------+--------------------+
| payee_id | payee_name         | 
+----------+--------------------+
| 1        | John Smith         | 
| 10       | Chen Lou           | 
| 11       | Mark Dello         |
| 12       | ANTRECCO           | 
| 13       | Shay Ridz          | 
+----------+--------------------+

我執行此查詢以連接兩個表，以在我的issue_details表中描述收款人姓名。

SELECT      
    issue_details.issue_date AS date,
    issue_details.check_no AS check_no,
    payees.payee_name AS payee 
FROM
    issue_details
INNER JOIN 
    payees ON issue_details.payee_id = payees.payee_id

結果 ：

+----------+------------+----------+
| check_no | issue_date | payee    | 
+----------+------------+----------+
|    34561 | 2015-01-24 | Chen Lou |       
|    34562 | 2015-01-24 | Shay Ridz|       
+----------+------------+----------+

如果我這樣做：

SELECT      
    issue_details.issue_date AS date,
    issue_details.check_no AS check_no,
    CONCAT(payees.payee_name, '', lddap_no) AS payee 
FROM
    issue_details
INNER JOIN 
    payees ON issue_details.payee_id = payees.payee_id

結果仍然與上面相同。 它不將payee_name （從表payees連接）的兩列和payee_name連接lddap_no 。

這是我想發生的事情：

+----------+------------+----------+
| check_no | issue_date | payee    |  
+----------+------------+----------+
|        0 | 2015-01-01 | 11101-15 |      
|        1 | 2015-01-24 | 11101-15 |     
|    34561 | 2015-01-24 | Chen Lou |
|    34562 | 2015-01-24 | Shay Ridz|     
+----------+------------+----------+

請在這里幫助我的查詢。 將不勝感激。 謝謝

Answer 1

SELECT      id.issue_date AS date,
            id.check_no AS check_no,
            COALESCE( p.payee_name, id.lddap_no ) AS payee 
FROM        issue_details id
            LEFT  JOIN payees p ON
            id.payee_id = p.payee_id

請參見SQLFiddle演示

Answer 2

只需將INNER JOIN更改為LEFT JOIN

SELECT      issue_details.issue_date AS date,
            issue_details.check_no AS check_no,
            payees.payee_name AS payee 
FROM
            issue_details
            LEFT JOIN payees ON
            issue_details.payee_id = payees.payee_id