MySQL左连接并有特定条件

Question

I have following tables that manage revenue

revenue Table

+------------+--------+--------+
| revenue_id | amount | status |
+------------+--------+--------+
|          1 |  45000 |      1 |
|          2 |  25000 |      1 |
|          3 |  67000 |      1 |
|          4 |  22000 |      1 |
|          5 |  32000 |      0 |
+------------+--------+--------+

bank Table

+---------+--------+-------------+-------------+
| bank_id | ref_no | bank_amount | bank_status |
+---------+--------+-------------+-------------+
|       1 |      2 |       23000 | Pending     |
|       2 |      3 |       67000 | Confirmed   |
|       3 |      4 |       22000 | Confirmed   |
+---------+--------+-------------+-------------+

02) If a revenue as mentioned in the revenue table has banked, it is recorded in the bank table. After that, the amounts in two tables are equal, the bank status may be into "Confirmed".

03) So, I need to get Confirmed records only as following by joining above two tables

Desired Output

+------------+--------+-------------+-------------+
| revenue_id | amount | bank_amount | bank_status |
+------------+--------+-------------+-------------+
|          3 |  67000 |       67000 | Confirmed   |
|          4 |  22000 |       22000 | Confirmed   |
+------------+--------+-------------+-------------+ 

Desired Output-02

+------------+--------+-------------+-------------+
| revenue_id | amount | bank_amount | bank_status |
+------------+--------+-------------+-------------+
|          1 |  45000 |             |             |
|          2 |  25000 |       23000 | Pending     |
|          3 |  67000 |       67000 | Confirmed   |
|          4 |  22000 |       22000 | Confirmed   |
+------------+--------+-------------+-------------+

Desired Output-03

+------------+--------+-------------+-------------+
| revenue_id | amount | bank_amount | bank_status |
+------------+--------+-------------+-------------+
|          1 |  45000 |             |             |
|          2 |  25000 |       23000 | Pending     |
+------------+--------+-------------+-------------+

04) To get the desired output I used the following query

select revenue.revenue_id, revenue.amount, bank.bank_amount, bank.bank_status 
from revenue
left join bank on bank.ref_no = revenue.revenue_id
where revenue.status = 1 and bank.bank_status = "Confirmed"

05) But did't get the expected result. It generated only the empty result. I can not understand what I am going wrong. Can any one help me ?

Answer 1

You have to use Inner Join instead of Left JOIN for your expected output.

SELECT revenue.revenue_id,
       revenue.amount,
       bank.bank_amount,
       bank.bank_status
FROM revenue
INNER JOIN bank ON bank.ref_no = revenue.revenue_id
WHERE revenue.status = 1
  AND bank.bank_status = "Confirmed"

DEMO

Answer 2

select revenue.revenue_id, revenue.amount, bank.bank_amount, bank.bank_status 
from revenue
Inner join (select * 
              From bank
              Where bank_status = "Confirmed") bank
on bank.ref_no = revenue.revenue_id

Answer 3

You have to use the first bank table and then revenue table for left join . Because in left join all rows will be returned even without matches.

So, use query like this. select revenue.revenue_id, revenue.amount, bank.bank_amount, bank.bank_status from bank left join revenue on bank.ref_no = revenue.revenue_id where revenue.status = 1 and bank.bank_status = "Confirmed"