MySQL - searching multiple schemas for particular value - mysql

Question

I have a server with multiple schemas. I need to find specyfic email address. Every schema looks pretty much te same, they have same structure. What i wanted to do is to write a script to for displaying dbname and specyfic data related to given email . Heres my script, but it do not work:(
DELIMITER $$
#Drop procedure if exists SearchAllDb $$
Create procedure SearchAllDb()
BEGIN
DECLARE DB_NAME Varchar(50);
DECLARE done INT default FALSE;
DECLARE CURSOR_ALL_DB_NAMES CURSOR FOR
SELECT schema_name from information_schema.schemata
WHERE schema_name like 'itools_%';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN CURSOR_ALL_DB_NAMES;
myloop: LOOP
FETCH CURSOR_ALL_DB_NAMES INTO DB_NAME;
IF done THEN LEAVE myloop;
END IF;
WHILE done != TRUE DO
SET #SQL = CONCAT('select DB_NAME, id, sn, name, email
from',DB_NAME,'.`open_cases` where email like 'xxx#yahoo.com'');
prepare stmt from #SQL;
execute stmt;
deallocate prepare stmt;
END WHILE;
CLOSE CURSOR_ALL_DB_NAMES;
END;
DELIMITER ;
I have something similar written in t-sql and it works...
DECLARE #DB_NAME VARCHAR(50);
DECLARE CURSOR_ALL_DB_NAMES CURSOR FOR
SELECT name FROM master.sys.databases
WHERE name like 'pickup-%' and name!= 'pickup-stored';
OPEN CURSOR_ALL_DB_NAMES;
FETCH NEXT FROM CURSOR_ALL_DB_NAMES INTO #DB_NAME
WHILE ##Fetch_Status = 0
BEGIN
Print #DB_NAME;
exec ('select '''+ #DB_NAME + ''' as db, id, sn, email from ['+
#DB_NAME+'].dbo.requests where email in (''xxx#live.com'')');
FETCH NEXT FROM CURSOR_ALL_DB_NAMES INTO #DB_NAME
END
CLOSE CURSOR_ALL_DB_NAMES;
DEALLOCATE CURSOR_ALL_DB_NAMES;

Answer 1

Looks like you were doing fine up until you introduced the WHILE.
THE WHILE is redundant since you are using a LOOP, you should remove those lines.
The LOOP doesn't have an END.
The CONCAT statement will treat the first use of DB_NAME as one of your column names and there are some quoting issues with the LIKE.
The ';' at the end of the procedure should be '$$' which you have specified as your DELIMITER.
I've taken a few liberties with your variable names but this tidied up version should illustrate the points.
DELIMITER $$
DROP PROCEDURE IF EXISTS SearchAllDb $$
CREATE PROCEDURE SearchAllDb()
BEGIN
DECLARE db_name VARCHAR(64);
DECLARE done INT DEFAULT FALSE;
DECLARE cur CURSOR FOR
SELECT schema_name
FROM information_schema.schemata
WHERE schema_name LIKE 'itools_%';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur;
myloop: LOOP
FETCH cur INTO db_name;
IF done THEN
LEAVE myloop;
END IF;
SET #SQL = CONCAT('SELECT ''', db_name, ''', id, sn, name, email
FROM `', db_name,'`.`open_cases`
WHERE email LIKE ''xxx#yahoo.com''');
PREPARE stmt FROM #SQL;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END LOOP;
CLOSE cur;
END $$
DELIMITER ;
There's a very good CURSOR example in the documentation at https://dev.mysql.com/doc/refman/5.7/en/cursors.html which will help you with the structure of the procedure.