how can implemented subquery in flink

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how can implemented subquery in flink

hager sallah
  how can implemented subquery in flinkexample
SELECT C_CUSTKEY,C_NAME
FROM Customers where C_MKTSEGMENT=(select C_CUSTKEY,C_MKTSEGMENT from Customers where C_ADDRESS="MG9kdTD2WBHm")    



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Re: how can implemented subquery in flink

Matthias J. Sax
If the sub-query is not correlated, you can (always) transform it into a
simple join query.

However, the query you show is no valid SQL... Did you mean:

SELECT C_CUSTKEY,C_NAME
FROM Customers
WHERE C_MKTSEGMENT =
  (SELECT C_MKTSEGMENT FROM Customers WHERE C_ADDRESS="MG9kdTD2WBHm")

In this case, you can transform it into:

SELECT c1.C_CUSTKEY, c1.C_NAME
FROM Customers AS c1, Customers AS c2
WHERE c1.C_MKTSEGMENT = c2.C_MKTSEGMENT
      AND c2.C_ADDRESS="MG9kdTD2WBHm"


-Matthias



On 05/05/2015 06:01 PM, hager sallah wrote:
>   how can implemented subquery in flinkexample
> SELECT C_CUSTKEY,C_NAME
> FROM Customers where C_MKTSEGMENT=(select C_CUSTKEY,C_MKTSEGMENT from Customers where C_ADDRESS="MG9kdTD2WBHm")    
>
>
>
>


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Re: how can implemented subquery in flink

hager sallah
From Customers AS c1, Customers AS c2
 this is two dataset how can use filter function implemented this


     On Tuesday, May 5, 2015 9:30 AM, Matthias J. Sax <[hidden email]> wrote:
   

 If the sub-query is not correlated, you can (always) transform it into a
simple join query.

However, the query you show is no valid SQL... Did you mean:

SELECT C_CUSTKEY,C_NAME
FROM Customers
WHERE C_MKTSEGMENT =
  (SELECT C_MKTSEGMENT FROM Customers WHERE C_ADDRESS="MG9kdTD2WBHm")

In this case, you can transform it into:

SELECT c1.C_CUSTKEY, c1.C_NAME
FROM Customers AS c1, Customers AS c2
WHERE c1.C_MKTSEGMENT = c2.C_MKTSEGMENT
      AND c2.C_ADDRESS="MG9kdTD2WBHm"


-Matthias



On 05/05/2015 06:01 PM, hager sallah wrote:
>  how can implemented subquery in flinkexample
> SELECT C_CUSTKEY,C_NAME
> FROM Customers where C_MKTSEGMENT=(select C_CUSTKEY,C_MKTSEGMENT from Customers where C_ADDRESS="MG9kdTD2WBHm")   
>
>
>
>