MySQL左外部联接和{？}

Question

I have been tasked with converting some Crystal SQL queries into QlikView and am having trouble deciphering the SQL code as it has been a decade since I last played with this. I'm modelling the data in MySQL workbench prior to importing it into QlikView.

I have posted the code bellow for the sake of completeness although I realize a lot of it is surplus.

The issue I am having is I don't know and cant seem to work out how do duplicate these queries in MySQL workbench as I don't understand what these code segments are doing: ={?APS: ITEM1.ST_Prodcode} and ={?FKE: ITEM1_1.ST_Prodcode} etc.

The above mentioned code appears to me to be calling the next query. Am I right in thinking this?

Pricing

SELECT 
`stock_management1`.`st_prodcode`, 
`stock_management1`.`st_sdesc`, 
`stock_management1`.`st_mstockist`, 
`stock_management1`.`APS_rol`, 
`stock_management1`.`APS_eoq`, 
`stock_management1`.`APS_ms`
FROM   
`pricing`.`stock_management` 
`stock_management1`
WHERE  
(`stock_management1`.`st_mstockist`='BRA' 
OR 
`stock_management1`.`st_mstockist`='FCS' 
OR 
`stock_management1`.`st_mstockist`='FKE') 
AND 
`stock_management1`.`APS_ms`>0 
AND 
(`stock_management1`.`st_prodcode`>='A' 
AND 
`stock_management1`.`st_prodcode`<='WZZZZZ999')
EXTERNAL JOIN
stock_management1.st_prodcode={?APS: ITEM1.ST_Prodcode} 
AND 
stock_management1.st_prodcode={?FCS: stocktake1.S_ProdCode} 
AND 
stock_management1.st_prodcode={?CENTRAL: Command.mv_PRODCODE}

APS

SELECT `ITEM1`.`ST_SOH`, `ITEM1`.`ST_Prodcode`
FROM   `aps`.`ITEM` `ITEM1`
WHERE  `ITEM1`.`ST_Prodcode`={?pricing: stock_management1.st_prodcode}
EXTERNAL JOIN ITEM1.ST_Prodcode={?FKE: ITEM1_1.ST_Prodcode}

FKE

SELECT `ITEM1_1`.`ST_SOH`, `ITEM1_1`.`ST_Prodcode`
FROM   `iewkelvin`.`ITEM` `ITEM1_1`
WHERE  `ITEM1_1`.`ST_Prodcode`={?APS: ITEM1.ST_Prodcode}
EXTERNAL JOIN ITEM1_1.ST_Prodcode={?FCS: ITEM1_2.ST_Prodcode}

Answer 1

Thanks for comments imran & ralfbecher.

I found that the {? implies WHERE followed by the Database: table.field

Simple as that really.