从多个与记录匹配的表中获取值，条件为mysql中的if条件

Question

enter image description here I am fetching data from 6 tables namely voucher,sourcing,procurement,vendor,market,farmer i am matching the id present in voucher table with sourcing and procurement table and retrieving data, my problem is in procurement table i when i get the source as farmer i want to get all the data from farmer table and with vendor and market tables also

I tried using inner join with switch case and inner query but i am getting error

SQL Query

SELECT voucher.voucher_id, sourcing.source_proc_id, procurement.procure_id,
case procurement.procure_from
    when 'farmer' then 
               (select procurement.procure_source, farmer.* from   procurement inner join farmer on 
procurement.procure_source =  farmer.farmer_id)
    ELSE 'No Data' END AS Result
  FROM vendor,market,farmer,
       ((voucher inner join sourcing on voucher.voucher_source_id =               sourcing.source_proc_id) inner join procurement on voucher.voucher_proc_id= procurement.procure_id) WHERE voucher.voucher_status = "ACTIVE" group by voucher.voucher_id

farmer table

 farmer_id | farmer_name | farmer_address
  -----------------------------------------
  F_001     | Name        | Address

vendor table

  vendor_id | vendor_name 
  -----------------------
  V_001     | Vendor

voucher table

 voucher_id | voucher_source_id | voucher_proc_id
  ------------------------------------------------
  VOUC_001   | SRC_001           | PROC_001

Procurement Table

procure_id | procure_from | procure_source
  -------------------------------------------
  PROC_001   | farmer       | F_001
  PROC_002   | vendor       | V_001

  Expected output voucher_id | voucher_source_id | procure_id | procure_from | procure_source | farmer_name ----------------------------------------------------------------------------------------- VOUC_001 | SRC_001 | PROC_001 | farmer | F_001 | Name 

Answer 1

Please tell what is the error you are getting.

In the meanwhile you may try the following. It is very hard for me to test whether it will work or not. So please tell the outcome and the previous error.

SELECT 
    voucher.voucher_id,
    sourcing.source_proc_id,
    procurement.procure_id,
    CASE
        WHEN
            procurement.procure_from = 'farmer'
        THEN
            (SELECT 
                    procurement.procure_source, farmer.*
                FROM
                    procurement
                        INNER JOIN
                    farmer ON procurement.procure_source = farmer.farmer_id)
        ELSE 'No Data'
    END AS Result
FROM
    vendor,
    market,
    farmer,
    ((voucher
    INNER JOIN sourcing ON voucher.voucher_source_id = sourcing.source_proc_id)
    INNER JOIN procurement ON voucher.voucher_proc_id = procurement.procure_id)
WHERE
    voucher.voucher_status = 'ACTIVE'
GROUP BY voucher.voucher_id;

I hope it works.