I have the following stored procedure in phpmyadmin
using mysql
:
CREATE DEFINER=`user`@`localhost` PROCEDURE `set_address`(IN `patient_street` VARCHAR(128), IN
`patient_city` VARCHAR(45), IN `patient_post_code` VARCHAR(45), IN `patient_state_or_province` VARCHAR(45), IN `patient_country` VARCHAR(45))
NOT DETERMINISTIC NO SQL SQL SECURITY
DEFINER
BEGIN
IF NOT EXISTS (SELECT a.address_id FROM address as a where a.street = patient_street and a.city = patient_city and a.post_code = patient_post_code and a.country = patient_country)
THEN
BEGIN
INSERT INTO address (street, city, post_code, state_or_province, country) VALUES (patient_street, patient_city, patient_post_code, patient_state_or_province, patient_country);
SELECT LAST_INSERT_ID();
END;
ELSE
BEGIN
SELECT a.address_id FROM address as a where a.street = patient_street and a.city = patient_city and a.post_code = patient_post_code and a.country = patient_country
END;
END IF;
END;
However, I got 2 errors in IF NOT EXISTS
:
Personally, if I had a requirement to write a procedure that performed the specified operations, and returned a resultset, I'd write it like this:
DELIMITER $$
CREATE DEFINER=`user`@`localhost` PROCEDURE `set_address`
(IN `patient_street` VARCHAR(128)
,IN `patient_city` VARCHAR(45)
,IN `patient_post_code` VARCHAR(45)
,IN `patient_state_or_province` VARCHAR(45)
,IN `patient_country` VARCHAR(45)
)
NOT DETERMINISTIC SQL SECURITY DEFINER
BEGIN
DECLARE li_address_id BIGINT DEFAULT NULL;
-- check for existing row and get address_id
SELECT a.address_id
INTO li_address_id
FROM address a
WHERE a.street = patient_street
AND a.city = patient_city
AND a.post_code = patient_post_code
AND a.country = patient_country
LIMIT 1 ;
-- if we didn't find a matching row
IF li_address_id IS NULL THEN
-- add a row and get the new address_id
INSERT INTO address (street, city, post_code, state_or_province, country) VALUES
(patient_street, patient_city, patient_post_code, patient_state_or_province, patient_country);
SELECT LAST_INSERT_ID() INTO li_address_id;
END IF;
-- return address_id (either found existing row, or newly added row) as a resultset
SELECT li_address_id AS address_id;
END$$
DELIMITER ;
If a row exists, we don't need to run two SELECT
statements. We can do the check for the row AND get the address_id with a single SELECT
.
If we didn't get a matching row, then we insert a row, and retrieve the auto-increment id.
In either case (found row, or added row), return the address_id as a resultset. Again, we can do that with a single SELECT statement, rather than two different statements.
To me, it makes more sense to limit the number of places we are returning resultsets, and limit the number of times we query the database.
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