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I am creating a function in postgresql which will do something like following:

CREATE OR REPLACE FUNCTION check_label_id_exist(_labelid integer, OUT result text) AS
$BODY$
DECLARE
BEGIN
    SELECT pkid FROM table_1 WHERE label_id = _labelid;
    IF FOUND THEN
    result := 'true';
    RETURN;
    IF NOT FOUND THEN
    SELECT pkid FROM table_2 WHERE label_id = _labelid;
    IF FOUND THEN
    result := 'true';
    RETURN;
    IF NOT FOUND THEN
    SELECT pkid FROM table_3 WHERE label_id = _labelid;
    IF FOUND THEN
    result := 'true';
    RETURN;
    IF NOT FOUND THEN
    result := 'false';

    RETURN;
END
$BODY$ language plpgsql;

Here the function looks for data in table_1 first. If no data then it will go to next table and so on. If any of the table has data it will break the condition and return true else finally it will return false. I think the code that I have written here is not correct. Please help to achieve my goal.

share|improve this question
    
@NeilMcGuigan Union could be a good idea. But I am not good on that. But obviously I would like to try. Can you please give me a sample. I just want to return true or false. If there have any result for any of the queries it will return true otherwise false. –  ray 19 hours ago

1 Answer 1

up vote 0 down vote 
CREATE OR REPLACE FUNCTION check_label_id_exist(_labelid integer,
    OUT result text) AS
$BODY$
DECLARE
BEGIN
    SELECT pkid FROM table_1 WHERE label_id = _labelid;
    IF FOUND THEN
        result := 'true';
        RETURN;
    end if;

    SELECT pkid FROM table_2 WHERE label_id = _labelid;
    IF FOUND THEN
        result := 'true';
        RETURN;
    end if;

    SELECT pkid FROM table_3 WHERE label_id = _labelid;
    IF FOUND THEN
        result := 'true';
        RETURN;
    end if;
    result := 'false';
    RETURN;
END
$BODY$ language plpgsql;
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