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I need to do a query in the MySQL, which returns different values ​​for the product_id, but I want to enter the 'id' field There is a need to pick and return which is in the specific table.

- I will use it differently and I want to use it on product_id and see id 

  SELECT DISTINCT id, product_id order_cart   
 it will be easy to do on Pgsql But I do not know how to do it on mysql.   
 
 
 Your query is not well defined: Consider this table  
  id product_id 1 1 2 2 3 1 4 2   
 What should be the result of your query? If you mean  
  id product_id 1 or 3 1 2 or 4 2   
 You are in the country of non-determinative questions.  
 What can you do  
  SELECT MIN (id), product_id order_cart GROUP BY product_id   
 which will definitely arise  
  id product_id 1 1 2 2

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