How use UPDATE in CONCAT() of PROCEDURE MySQL - mysql

Question

I try update exist tables via PROCEDURE. But I get an error: MySQL: #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= iOS, phone_manufacture = Apple, phone_model = iPhone, os_vers = iOS X.X' at line 1
My Procedure:
BEGIN
DECLARE a, b INT;
DECLARE a1, a2, a3, a4 TEXT;
DECLARE cur1 CURSOR FOR SELECT id FROM z7_group;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET b = 1;
OPEN cur1;
SET b = 0;
SET a1 = "iOS";
SET a2 = "Apple";
SET a3 = "iPhone";
SET a4 = "iOS X.X";
WHILE b = 0 DO
FETCH cur1 INTO a;
IF b = 0 THEN
SET #data_ all_group = (SELECT `myTables` FROM `all_group` WHERE id= a);
SET #s = CONCAT('UPDATE ', #data_ all_group, 'SET `os` = ',a1,', `phone_manufacture` = ',a2,', `phone_model` = ',a3', `os_vers` = ',a4,');
PREPARE stmt3 FROM #s;
EXECUTE stmt3;
END IF;
END WHILE;
CLOSE cur1;
END;

Answer 1

You have two options:
(there is more but I think it is what you want)
Enclose values in single quotes at inicialization:
SET a1 = "'iOS'";
SET a2 = "'Apple'";
SET a3 = "'iPhone'";
SET a4 = "'iOS X.X'";
and fix the sentence:
CONCAT('UPDATE ', #data_all_group, ' SET `os` = ',a1,', `phone_manufacture` = ',a2,', `phone_model` = ',a3,', `os_vers` = ',a4)
The result will be:
UPDATE your_table SET `os` = 'iOS', `phone_manufacture` = 'Apple', `phone_model` = 'iPhone', `os_vers` = 'iOS X.X'
OR: fix the query build:
SET #s = CONCAT('UPDATE ', #data_all_group
, "SET `os` = '" , a1 ,"',"
, "`phone_manufacture` = '",a2,"',"
, "`phone_model` = '",a3,"',"
, "`os_vers` = '",a4,"'");