Mysql database table cursor

Question

i have written the function below containing a cursor while executing it an error appears . what' wrong please

CREATE PROCEDURE processorders()
BEGIN
   DECLARE ordernumbers CURSOR FOR 
     SELECT * FROM psdms_feature_product 

   dept_rec ordernumbers%ROWTYPE
   o ordernumbers%ROWTYPE

   OPEN ordernumbers
   REPEAT
    FETCH ordernumbers INTO o

    IF (o.id_product ) THEN
      IF (o.id_feature  == 510) THEN
        update    psdms_feature_value_lang t1
        LEFT JOIN psdms_feature_product t2
        ON        t1.id_feature_value = t2.id_feature_value
        SET       value ='95090€'
        WHERE     t2.id_product = 1 
        AND       t2.id_feature = 510
      ELSE
        insert into psdms_feature_value ( id_feature ) values (510);
        insert into psdms_feature_product ( id_feature, id_product , id_feature_value) 
        values (o.id_feature , o.id_product , o.id_feature_value )
      END IF
    END IF

   UNTIL done END REPEAT
   CLOSE ordernumbers
END
END

Answer 1

Better is to avoid cursors. Remember that SQL loves to do things in bulk, but hates to work with Cursors.

UPDATE  psdms_feature_value_lang t1
    JOIN  ordernumbers AS o  ON ...
    LEFT JOIN  psdms_feature_product t2
          ON t1.id_feature_value = t2.id_feature_value SET
    value  ='95090€'
    WHERE  t2.id_product = 1
      AND  t2.id_feature = 510
      AND  o.id_product
      AND  o.id_feature = 510;
INSERT
     INTO  psdms_feature_value ( id_feature ) 
SELECT  510
    FROM  ordernumbers
    WHERE  o.id_product
      AND  o.id_feature = 510;
INSERT
     INTO  psdms_feature_product ( id_feature, id_product, id_feature_value) 
SELECT  o.id_feature , o.id_product , o.id_feature_value
    FROM  ordernumbers
    WHERE  o.id_product
      AND  o.id_feature = 510;

Index:

ordernumbers: INDEX(id_feature, id_product, id_feature_value)

Other notes:

== is not proper syntax

What do you mean by AND id_product? It probably tests for non-zero.