CODEWITHSUNDEEP
mysqlstored-procedurescursor
Paul Barclay
Paul Barclay

Reputation: 499

MySQL stored procedure looping control

I am looping over a cursor and have the standard exist loop control set however in the loop I also do select into from another table, if this search returns no results then that triggers the exit handler and the loop terminates.

My question is: How do I attached the continue handler for the loop to a cursor and ignore the select into or how do I get round this problem?

DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_results=1;
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.   
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search_loop:WHILE (no_more_results=0) DO
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 FETCH my_csr INTO something;
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    SELECT thing INTO my_thing FROM `dups` where `dups`.thing = thing_id;

The last select triggers the exit conditions...

Thanks Paul

Upvotes: 1

Views: 742

Answers (1)

Bohemian
Bohemian

Reputation: 425448

Since your code is expecting zero or one rows, use the SET syntax:

SET my_thing = (SELECT thing FROM dups where dups.thing = thing_id);

This will set my_thing to null if there are no rows.

I haven't tested this, so if it is still setting the handler, change to this, which always returns a row:

SET my_thing = SELECT IFNULL((SELECT thing FROM dups where dups.thing = thing_id), null);

Alternatively, you can convert your statement similarly:

SELECT IFNULL((SELECT thing FROM dups where dups.thing = thing_id), null) INTO my_thing;


I believe these alternatives are presented in order of readability.

Upvotes: 2

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