MySQL - implement Windows Function like logic in MySQL 5.6 version ( windows fn is there fro 8.0)

 MySQL - WINDOWS FUNCTION Implementation without Windows function 

#this is needed in MySQL version below version 8.0 

Scenario:

There are records with seemingly PrimaryKey column (cant make it PK, and so duplicate can come in) , a ForeignKey and createTImestamp --> want to make sure that processing happens only once for the primaryKey  - if there are duplicate entries - only way to find it is from  the order of create timestamp and if processed already, foreignKey column will have value.

So want to ientify is there was a prior ForeignKey assigned - which means -   its already processed --- AND  if at all there are 2 entries which are not processed yet, make sure to process just the first one and mark other one as cancelled

https://stackoverflow.com/questions/17939198/row-number-per-group-in-mysql 

SELECT id,
     crew_id,
     amount,
     CASE type 
         WHEN @curType THEN @curRow := @curRow + 1 
         ELSE @curRow := 1
     END AS rank,
     @curType := type AS type
FROM Table1 p
JOIN (SELECT @curRow := 0, @curType := '') r
ORDER BY crew_id, type

### Getting the rank based on execId & createTimestamp

SELECT foreignId, createTimestamp,

		CASE executionId 
			WHEN @curType THEN @curRow := @curRow + 1 
			ELSE @curRow := 1 
		END AS rank,
        @curType := executionId AS executionId
FROM  job_queue_prd p
JOIN (SELECT @curRow := 0, @curType := '') r
WHERE p.executionID in (204626, 204851) 
ORDER BY  executionId, createTimestamp asc;

### Getting current & prior instanceId & the rank based on execId  & createTimestamp
SET @instanceId=0;
SELECT foreignId, createTimestamp, @instanceId prior_foreignId, @foreignId:=foreignId foreignId,
		CASE executionId 
			WHEN @curExecId THEN @curRow := @curRow + 1 ELSE @curRow := 1 
		END AS rank,
        @curExecId := executionId AS executionId
FROM  job_queue_prd p
JOIN (SELECT @curRow := 0, @curExecId := '') r
WHERE p.executionID in (204626, 204851) 
ORDER BY  executionId, createTimestamp asc;