mysql cursor using USE mydb; - mysql

Question

I appreciate your answer. I changed the procedure with your changes, but I've done something wrong. Would you please tell me what is wrong with the code?
So I'll need to include the code at the end of the main question.
Attempt #2 is at the bottom.
Can someone tell me what is wrong with this procedure? The system tells me there is an error at:
DECLARE myemail_cursor CURSOR FOR
USE v_db; SELECT DISTINCT u.mail FROM users u INNER JOIN users_roles ur ON u.uid=ur.uid INNER JOIN role r ON ur.rid=r.rid WHERE r.name = 'court administrator' AND from_unixtime(u.access) >= NOW() - INTERVAL 1 YEAR;
If I run USE mydb; SELECT...in a query it works fine. Can I not use 'USE variable; select...' in a procedure?
BEGIN
DECLARE v_finished, v_finished1 BOOLEAN DEFAULT FALSE;
DECLARE v_email varchar(4000) DEFAULT "";
DECLARE v_db varchar(400) DEFAULT "";
DECLARE mydb_cursor CURSOR FOR
SELECT TABLE_SCHEMA AS 'database' FROM information_schema.TABLES WHERE TABLE_TYPE = 'BASE TABLE' and table_name='users';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_finished = TRUE;
open mydb_cursor;
get_mydb: LOOP
FETCH FROM mydb_cursor INTO v_db;
IF v_finished THEN
CLOSE mydb_cursor;
LEAVE get_mydb;
END IF;
DECLARE myemail_cursor CURSOR FOR
USE v_db; SELECT DISTINCT u.mail FROM users u INNER JOIN users_roles ur ON u.uid=ur.uid INNER JOIN role r ON ur.rid=r.rid WHERE r.name = 'court administrator' AND from_unixtime(u.access) >= NOW() - INTERVAL 1 YEAR;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_finished1 = TRUE;
OPEN myemail_cursor;
get_myemail: LOOP
FETCH FROM myemail_cursor INTO v_email';
IF v_finished1 THEN
CLOSE myemail_cursor;
SET v_finished1 = FALSE;
LEAVE get_myemail;
END IF;
-- build email list
SET email_list = CONCAT(v_email," ",email_list);
END LOOP get_myemail;
CLOSE myemail_cursor;
END LOOP get_email;
CLOSE email_cursor;
END LOOP get_mydb;
END
Attempt #2.
I am getting this error: table 'v_db.users' doesn't exist
The first cursor only selects DBs where the table users exists, so I can't figure out why I"m getting the error.
BEGIN
DECLARE v_finished, v_finished1 BOOLEAN DEFAULT FALSE;
DECLARE v_email varchar(4000) DEFAULT "";
DECLARE v_db varchar(400) DEFAULT "";
DECLARE mydb_cursor CURSOR FOR
SELECT TABLE_SCHEMA AS 'database' FROM information_schema.TABLES WHERE TABLE_TYPE = 'BASE TABLE' and table_name='users';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_finished = TRUE;
open mydb_cursor;
get_mydb: LOOP
FETCH FROM mydb_cursor INTO v_db;
IF v_finished THEN CLOSE mydb_cursor;
LEAVE get_mydb;
END IF;
BLOCK2: BEGIN
DECLARE myemail_cursor CURSOR FOR
SELECT DISTINCT u.mail FROM v_db.users u INNER JOIN v_db.users_roles ur ON u.uid=ur.uid INNER JOIN v_db.role r ON ur.rid=r.rid WHERE r.name = 'court administrator' AND from_unixtime(u.access) >= NOW() - INTERVAL 1 YEAR;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_finished1 = TRUE;
OPEN myemail_cursor;
get_myemail: LOOP
FETCH FROM myemail_cursor INTO v_email;
IF v_finished1 THEN
CLOSE myemail_cursor;
LEAVE get_myemail;
END IF;
SET email_list = CONCAT(v_email," ",email_list);
END LOOP get_myemail;
END BLOCK2;
END LOOP get_mydb;
END

Answer 1

23.2.1 Stored Routine Syntax
...
When the routine is invoked, an implicit USE db_name is performed (and undone when the routine terminates). USE statements within stored routines are not permitted.
...
Try:
...
DECLARE mydb_cursor CURSOR FOR
SELECT
DISTINCT u.mail
FROM
v_db.users u
INNER JOIN v_db.users_roles ur ON u.uid=ur.uid
INNER JOIN v_db.role r ON ur.rid=r.rid
WHERE
r.name = 'court administrator' AND
from_unixtime(u.access) >= NOW() - INTERVAL 1 YEAR;
...
Remember:
13.6.3 DECLARE Syntax
...
DECLARE is permitted only inside a BEGIN ... END compound statement and must be at its start, before any other
statements.
...