I have a situation in which I would like to iterate through a "schedPayments" table that stores a schedule of payments corresponding with a client in the "client" table. The client table also contains a "status" column at the moment holds a 0 for "Past Due" and a 1 for "Current". When the balance from the client table is greater than the supposed balance from the schedPayments table AND today's date is later than the date the payment was scheduled for, the status column in the clients table should be set to 0.
I may be completely off the wall with my solution, but I keep getting Error Code: 1329. No Data - zero rows fetched, selected or processed. The MySQL Workbench lacks some major debugging capabilities that I wish it had. The documentation also doesn't quite cover what I need either in this situation.
CREATE PROCEDURE `project`.`status_update` ()
BEGIN
DECLARE balance DECIMAL(20) DEFAULT 0;
DECLARE cID INT(10) DEFAULT 0;
DECLARE currentID INT(10) DEFAULT 0;
DECLARE supposedBal DECIMAL(20) DEFAULT 0;
DECLARE payDate DATE;
DECLARE cur1 CURSOR FOR SELECT ClientID,SupposedBalance,Date FROM project.schedpayments;
OPEN cur1;
status_loop: LOOP
FETCH cur1 INTO cID, supposedBal, payDate;
BLOCK2: BEGIN
DECLARE cur2 CURSOR FOR SELECT balance FROM project.client WHERE ID=cID;
OPEN cur2;
FETCH cur2 INTO balance;
IF currentID > cID THEN
SET currentID = cID;
IF (CURDATE() > payDate) AND (supposedBal < balance) THEN
UPDATE feeagree SET Status=0 WHERE ID=cID;
END IF;
CLOSE Cur2;
END IF;
END BLOCK2;
END LOOP;
CLOSE cur1;
END $$
You can see the remnants of how I had enclosed the entire procedure in a block and that only resulted in the compiler thinking the first block ended with END BLOCK2; and that resulted in an Error Code 1325. Cursor is already open.
I am definitely making this more complicated than necessary, so any help would be much appreciated. The only way I learn this stuff is trial by fire, and it is super hot today.
It seems that you don't need all those cursors and you can achieve your goal with one UPDATE statement.
It's hard to be precise without seeing your tables structures and sample data, but a more succinct version of your SP might look like this
CREATE PROCEDURE status_update()
UPDATE feeagree
SET Status = 0
WHERE ID IN
(
SELECT p.cID
FROM schedpayments p JOIN client c
ON p.cID = p.ID
WHERE p.Date < CURDATE()
AND p.SupposedBalance < c.balance
GROUP BY p.cID
);
...
DECLARE done TINYINT DEFAULT FALSE;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET DONE = true;
OPEN cur1;
status_loop: LOOP
FETCH cur1 INTO cID, supposedBal, payDate;
IF DONE = true THEN LEAVE status_loop; END IF;
...
SET DONE = false;
END LOOP;
The SET DONE = false at the end resets DONE in case anything in the inner block results in it getting set to TRUE;
Related
I'm trying to implement a cursor in MYSQL. Inside that cursor, I have a select statement that might or might not return any rows.
I'm facing a problem when that query does not return any rows.
According to the MYSQL documentation,
NOT FOUND: Shorthand for the class of SQLSTATE values that begin with '02'. This is relevant within the context of cursors and is used to control what happens when a cursor reaches the end of a data set. If no more rows are available, a No Data condition occurs with SQLSTATE value '02000'. You can set up a handler for it or a NOT-FOUND condition to detect this condition. For another example, see Section 13.6.6, “Cursors”. The NOT FOUND condition also occurs for SELECT ... INTO var_list statements that retrieve no rows.
My termination of the cursor is implemented as usual.
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET FINISHED = 1;
The problem is that the termination is triggered because of the query inside the cursor returning 0 rows. Is there a way to differentiate between those two cases so that the cursor continues despite my query returning 0 results?
Thanks in advance.
DROP PROCEDURE IF EXISTS CURSOR_PLACEHOLDER;
DELIMITER $$
CREATE PROCEDURE CURSOR_PLACEHOLDER()
BEGIN
DECLARE FINISHED INTEGER DEFAULT 0;
DECLARE CURRENT_ROW_ID VARCHAR(256);
DEClARE CURRENT_ROW
CURSOR FOR
SELECT ID
FROM A
WHERE ID_P IN (SELECT ID_P
FROM A
GROUP BY ID_P
HAVING COUNT(ID_P) > 1);
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET FINISHED = 1;
OPEN CURRENT_ROW;
GET_ACTION:
LOOP
FETCH CURRENT_ROW INTO CURRENT_ROW_ID;
IF FINISHED = 1 THEN
LEAVE GET_ACTION;
END IF;
SET #CURRENT_P_ID := (SELECT ID_P FROM A WHERE ID = CURRENT_ROW_ID);
SELECT a.ID_U, a.ID_R, a.A, a.FROMDATE, a.TODATE
INTO #ID_U, #ID_R, #A, #FROM_DATE, #TO_DATE
FROM ASSIG a
WHERE a.ID_G = #CURRENT_P_ID; # <- Query that returns 0 rows and terminates the cursor
IF (#ID_U IS NOT NULL) THEN
SET #ASSIG_ID := GENERATE_ID();
INSERT INTO ASSIG
VALUES (#ASSIG_ID,
#G_ID,
#ID_U,
#ID_R,
#A,
#FROM_DATE,
#TO_DATE);
END IF;
UPDATE A
SET ID_P = #G_ID
WHERE ID = CURRENT_ROW_ID;
END LOOP GET_ACTION;
CLOSE CURRENT_ROW;
END
$$
DELIMITER ;
I have created stored-procedure with OUT parameter to handle automate INSERT operations based on values of other tables. I also made stored-function for the same operation. I am facing a problem with execution time for both is heavily different which makes me worried and I don't know why is that.
Following table values in summary:
2016 rows in emp_personal
I am using MariaDB 10.3.14. I am testing with HeidiSQL 10.1.0.5577.
I also tried calling it from Node.JS using MariaDB Node.js Connector. But in both cases, I had almost the same result.
This is Stored Procedure
CREATE DEFINER=`root`#`localhost` PROCEDURE `sp_auto_attendance`(
OUT `result` INT
)
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN
DECLARE empId,done,isHoliday,isEmpHoliday,isWeekOff,isApprovedLeave,insertedRows INT DEFAULT 0;
DECLARE attendance VARCHAR(20) DEFAULT 'Present';
DECLARE empIds VARCHAR(500) DEFAULT '';
-- declare cursor with all employee Ids who are active
DECLARE empIds_cursor CURSOR FOR
SELECT id from emp_personal where isActive=1;
-- declare NOT FOUND handler
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
-- Check if today is holiday
SELECT COUNT(id) INTO isHoliday
FROM apexa_portal.public_holiday_dates
WHERE dateOfHoliday= CURDATE();
OPEN empIds_cursor;
get_id: LOOP
SET attendance = 'Present';
FETCH empIds_cursor INTO empId;
-- Following check if NOT FOUND handler has called, if yes exit loop else continue. NOTE: If you don't write this, it will be infinite loop.
IF done = 1 THEN
LEAVE get_id;
END IF;
-- Check if public holiday for employee
IF isHoliday > 0 THEN
SELECT COUNT(phtd.isActive) INTO isEmpHoliday FROM public_holiday_template_days as phtd
LEFT JOIN emp_office_details as eod ON eod.publicHolidayTemplate=phtd.templateId
LEFT JOIN public_holiday_dates as phd ON phd.pub_holiday_id=phtd.holidayId
WHERE eod.empID=empId AND phd.dateOfHoliday=CURDATE() AND phtd.isActive=1;
IF isEmpHoliday > 0 THEN
SET attendance = 'Public Holiday';
END IF;
END IF;
-- if not public holiday, Check if week off
IF attendance <> 'Public Holiday' THEN
SELECT COUNT(eowd.id) INTO isWeekOff FROM emp_office_working_days as eowd
WHERE DAY=DAYOFWEEK(CURDATE()) AND eowd.empId=empId AND eowd.isActive=0;
IF isWeekOff > 0 THEN
SET attendance = 'Week Off';
END IF;
END IF;
-- if not week off, Check if approved leave
IF attendance <> 'Week Off' THEN
SELECT COUNT(la.id) INTO isApprovedLeave FROM leave_application as la
WHERE la.fromDate <= CURDATE() AND la.toDate >= CURDATE() AND la.empID=empId AND la.leaveStatus='Approved';
IF isApprovedLeave > 0 THEN
SET attendance = 'Approved Leave';
END IF;
END IF;
-- insert attendance
INSERT INTO attendance_master(empID,dateOfAttendance,attendance) VALUES(empId,CURDATE(),attendance);
SET insertedRows = insertedRows + 1;
END LOOP get_id;
CLOSE empIds_cursor;
SET result = insertedRows;
END
This is Stored Function
CREATE DEFINER=`root`#`localhost` FUNCTION `test_auto_att_func`()
RETURNS int(11)
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN
DECLARE empId,done,isHoliday,isEmpHoliday,isWeekOff,isApprovedLeave,insertedRows INT DEFAULT 0;
DECLARE attendance VARCHAR(20) DEFAULT 'Present';
DECLARE empIds VARCHAR(500) DEFAULT '';
-- declare cursor with all employee Ids who are active
DECLARE empIds_cursor CURSOR FOR
SELECT id from emp_personal where isActive=1;
-- declare NOT FOUND handler
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
-- Check if today is holiday
SELECT COUNT(id) INTO isHoliday
FROM apexa_portal.public_holiday_dates
WHERE dateOfHoliday= CURDATE();
OPEN empIds_cursor;
get_id: LOOP
SET attendance = 'Present';
FETCH empIds_cursor INTO empId;
-- Following check if NOT FOUND handler has called, if yes exit loop else continue. NOTE: If you don't write this, it will be infinite loop.
IF done = 1 THEN
LEAVE get_id;
END IF;
-- Check if public holiday for employee
IF isHoliday > 0 THEN
SELECT COUNT(phtd.isActive) INTO isEmpHoliday FROM public_holiday_template_days as phtd
LEFT JOIN emp_office_details as eod ON eod.publicHolidayTemplate=phtd.templateId
LEFT JOIN public_holiday_dates as phd ON phd.pub_holiday_id=phtd.holidayId
WHERE eod.empID=empId AND phd.dateOfHoliday=CURDATE() AND phtd.isActive=1;
IF isEmpHoliday > 0 THEN
SET attendance = 'Public Holiday';
END IF;
END IF;
-- if not public holiday, Check if week off
IF attendance <> 'Public Holiday' THEN
SELECT COUNT(eowd.id) INTO isWeekOff FROM emp_office_working_days as eowd
WHERE DAY=DAYOFWEEK(CURDATE()) AND eowd.empId=empId AND eowd.isActive=0;
IF isWeekOff > 0 THEN
SET attendance = 'Week Off';
END IF;
END IF;
-- if not week off, Check if approved leave
IF attendance <> 'Week Off' THEN
SELECT COUNT(la.id) INTO isApprovedLeave FROM leave_application as la
WHERE la.fromDate <= CURDATE() AND la.toDate >= CURDATE() AND la.empID=empId AND la.leaveStatus='Approved';
IF isApprovedLeave > 0 THEN
SET attendance = 'Approved Leave';
END IF;
END IF;
-- insert attendance
INSERT INTO attendance_master(empID,dateOfAttendance,attendance) VALUES(empId,CURDATE(),attendance);
SET insertedRows = insertedRows + 1;
END LOOP get_id;
CLOSE empIds_cursor;
RETURN insertedRows;
END
Time to execute Stored Function
SELECT `test_auto_att_func`();
/* Affected rows: 0 Found rows: 1 Warnings: 0 Duration for 1 query: 0.328 sec. */
Time to execute Stored Procedure
CALL `sp_auto_attendance`(#res);
SELECT #res;
/* Affected rows: 6,049 Found rows: 1 Warnings: 0 Duration for 2 queries: 00:01:21.6 */
Stored Function Output and Stored Procedure Output
Can anyone please explain why this is happening? And if I am doing anything wrong, please let me know how should I correct it?
Thank You.
There should be no difference on performance on similar code when you run the code as a procedure vs as a function.
Most likely explanation (see Affected rows) is that at the the time of the function run, the cursor did not find any active persons whereas in the procedure run did, hence running the loop queries.
I have a medium sized stored procedure going on here below. My problem is that it doesn't do anything and I have no idea why.
1.) First of all, the code:
DROP PROCEDURE IF EXISTS deleteabundant_fixshared_shiftResources;
DELIMITER //
CREATE PROCEDURE deleteabundant_fixshared_shiftResources ()
BEGIN
DECLARE finish_flag BOOLEAN DEFAULT FALSE;
DECLARE id INT(11);
DECLARE startTime DATETIME;
DECLARE endTime DATETIME;
DECLARE shid INT(11);
DECLARE resid INT(11);
DECLARE id_inner INT(11);
DECLARE startTime_inner DATETIME;
DECLARE endTime_inner DATETIME;
DECLARE shid_inner INT(11);
DECLARE resid_inner INT(11);
DECLARE cr130 CURSOR FOR SELECT shift_resource_id, start_date, end_date, shift_id, resource_id FROM temp_shift_resource;
DECLARE cr131 CURSOR FOR SELECT shift_resource_id, start_date, end_date, shift_id, resource_id FROM temp_shift_resource;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET finish_flag = TRUE;
START TRANSACTION;
OPEN cr130;
OPEN cr131;
OUTERLOOP: LOOP
FETCH cr130 into id, startTime, endTime, shid, resid;
IF finish_flag THEN LEAVE OUTERLOOP; END IF;
INNERLOOP: LOOP
FETCH cr131 INTO id_inner, startTime_inner, endTime_inner, shid_inner, resid_inner;
IF finish_flag THEN LEAVE INNERLOOP; END IF;
IF (id!=id_inner) THEN
IF (resid=resid_inner AND shid_inner!=9) THEN
-- logic to determine if the dates are wrong:
IF (startTime<=startTime_inner AND endTime>=endTime_inner) THEN
INSERT INTO repairchange ( shift_resource_id, changetype, shift_id, resource_id, start_date, end_date )
VALUES ( id_inner, "FD", shid_inner, resid_inner, startTime_inner, endTime_inner );
DELETE FROM temp_shift_resource WHERE shift_resource_id = id_inner;
ELSEIF (endTime>=endTime_inner AND startTime<=endTime_inner) THEN
INSERT INTO repairchange ( shift_resource_id, changetype, shift_id, resource_id, start_date, end_date )
VALUES ( id_inner, "FU", shid_inner, resid_inner, startTime_inner, endTime_inner );
UPDATE temp_shift_resource set endTime_inner=(startTime - INTERVAL 1 DAY) where shift_resource_id = id_inner;
ELSEIF (startTime<=startTime_inner AND endTime>=startTime_inner) THEN
INSERT INTO repairchange ( shift_resource_id, changetype, shift_id, resource_id, start_date, end_date )
VALUES ( id_inner, "FU", shid_inner, resid_inner, startTime_inner, endTime_inner );
UPDATE temp_shift_resource set startTime_inner=(endTime + INTERVAL 1 DAY) where shift_resource_id = id_inner;
END IF;
END IF;
END IF;
END LOOP INNERLOOP;
SET finish_flag = FALSE;
END LOOP OUTERLOOP;
CLOSE cr130;
CLOSE cr131;
COMMIT;
END //
DELIMITER ;
call deleteabundant_fixshared_shiftResources();
2.) Description of what I want to do:
Basically, I have a table full of workshifts. Due to code bugs, some of these shifts have a wrong date assigned to them, and I have to fix the database.
I have to run through the whole table, and compare the rows that are assigned to the same resource_id, which represents a person. So if a person has two shifts that look like (2016-05-10 to 2016-05-20) and (2016-05-15 to 2016-05-23) for example, I have to fix it so that one of them will be trimmed to (2016-05-10 to 2016-05-14) and (2016-05-15 to 2016-05-23).
A shift that is a nightshift, marked as shift_id=9, must not be modified at all.
I insert rows into the repairchange table if a change or a deletion has been made
3.) The procedure runs, but does nothing. I have examples in the database for wrong rows, one example is the one I wrote above. I suspect it is the nested loop, because I want to loop and fetch through the same table, but I haven't found anything on that.
I got the message
0 row(s) affected, 1 warning(s): 1329 No data - zero rows fetched, selected, or processed
but I have seen this before and my stored procedures have worked even though they output this warning.
Any ideas or tips are welcome. Thank you for your time!
I figured it out, after quite some debugging:
I opened the cursors before both of the loops. This meant that after the first walk-through of the inner loop, the cursor was standing at +1 of the LAST row of the table, and when the new outer loop iteration started the second inner loop iteration, the cursor was still at the end position.
Thus it did not run. I replaced the inner-cursor opening and closing into the outer loop, and now it works properly.
I am writing a MySQL Stored Procedure for the first time, and I am running into an issue - I think with the Handler Code. Basically, I want this code to update all rows in the pps_users table, but for some reason I am hitting the 'finished condition' for the handler after only two rows are fetched.
I tried the same thing with the REPEAT syntax and got the same result. If I just run the cursor query I correctly get the 10,000 records I expect, but when I run the whole thing as is, I hit the finished code after only 1 or 2 records.
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `changeNFLFavTeams`()
BEGIN
DECLARE favNFLTeam varchar(100) DEFAULT "";
DECLARE favNCAATeam varchar(100) DEFAULT "";
DECLARE v_finished INTEGER DEFAULT 0;
DECLARE user_id bigint(20);
DECLARE fullNameOfTeam varchar(100) DEFAULT "";
DECLARE update_favs CURSOR FOR select id, favorite_nfl_team from pps_users WHERE favorite_nfl_team is not null;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_finished = 1;
OPEN update_favs;
updaterecord: LOOP
FETCH update_favs INTO user_id, favNFLTeam;
select user_id, favNFLTeam as "Test";
if v_finished = 1
then
select "finished" as "finished";
LEAVE updaterecord;
end if;
select full_name into fullNameOfTeam
from teams t
inner join display_names dt on dt.entity_id = t.id
and dt.entity_type = 'teams'
and dt.first_name = favNFLTeam
and team_key like 'l.nfl.com%' LIMIT 1;
select user_id, fullNameOfTeam AS "BeforeUpdate";
IF fullNameOfTeam != ''
THEN
-- here for whatever_transformation_may_be_desired
-- Find the Full name for the record they chose
UPDATE pps_users p
SET favorite_nfl_team = fullNameOfTeam
WHERE user_id = p.id;
ELSE
SELECT 'A' AS 'A'; -- no op
END IF;
end loop updaterecord;
CLOSE update_favs;
END
This is because if your SELECT full_name into fullNameOfTeam... query returns no rows, then it will set v_finished to 1. That, apparently, happens early on, and forces an exit from the main loop.
The key is to realize that the CONTINUE HANDLER for NOT FOUND does not apply to the cursor alone.
You should either put the secondary query into its own BEGIN..END block with its own CONTINUE handler, or (easier) just set v_finished = 0 after the SELECT full_name into fullNameOfTeam... statement.
How can I use two cursors in the same routine? If I remove the second cursor declaration and fetch loop everthing works fine. The routine is used for adding a friend in my webapp. It takes the id of the current user and the email of the friend we want to add as a friend, then it checks if the email has a corresponding user id and if no friend relation exists it will create one. Any other routine solution than this one would be great as well.
DROP PROCEDURE IF EXISTS addNewFriend;
DELIMITER //
CREATE PROCEDURE addNewFriend(IN inUserId INT UNSIGNED, IN inFriendEmail VARCHAR(80))
BEGIN
DECLARE tempFriendId INT UNSIGNED DEFAULT 0;
DECLARE tempId INT UNSIGNED DEFAULT 0;
DECLARE done INT DEFAULT 0;
DECLARE cur CURSOR FOR
SELECT id FROM users WHERE email = inFriendEmail;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cur;
REPEAT
FETCH cur INTO tempFriendId;
UNTIL done = 1 END REPEAT;
CLOSE cur;
DECLARE cur CURSOR FOR
SELECT user_id FROM users_friends WHERE user_id = tempFriendId OR friend_id = tempFriendId;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cur;
REPEAT
FETCH cur INTO tempId;
UNTIL done = 1 END REPEAT;
CLOSE cur;
IF tempFriendId != 0 AND tempId != 0 THEN
INSERT INTO users_friends (user_id, friend_id) VALUES(inUserId, tempFriendId);
END IF;
SELECT tempFriendId as friendId;
END //
DELIMITER ;
Here is a simple example of how to use two cursors in the same routine:
DELIMITER $$
CREATE PROCEDURE `books_routine`()
BEGIN
DECLARE rowCountDescription INT DEFAULT 0;
DECLARE rowCountTitle INT DEFAULT 0;
DECLARE updateDescription CURSOR FOR
SELECT id FROM books WHERE description IS NULL OR CHAR_LENGTH(description) < 10;
DECLARE updateTitle CURSOR FOR
SELECT id FROM books WHERE title IS NULL OR CHAR_LENGTH(title) <= 10;
OPEN updateDescription;
BEGIN
DECLARE exit_flag INT DEFAULT 0;
DECLARE book_id INT(10);
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET exit_flag = 1;
updateDescriptionLoop: LOOP
FETCH updateDescription INTO book_id;
IF exit_flag THEN LEAVE updateDescriptionLoop;
END IF;
UPDATE books SET description = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.' WHERE books.id = book_id;
SET rowCountDescription = rowCountDescription + 1;
END LOOP;
END;
CLOSE updateDescription;
OPEN updateTitle;
BEGIN
DECLARE exit_flag INT DEFAULT 0;
DECLARE book_id INT(10);
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET exit_flag = 1;
updateTitleLoop: LOOP
FETCH updateTitle INTO book_id;
IF exit_flag THEN LEAVE updateTitleLoop;
END IF;
UPDATE books SET title = 'Lorem ipsum dolor sit amet' WHERE books.id = book_id;
SET rowCountTitle = rowCountTitle + 1;
END LOOP;
END;
CLOSE updateTitle;
SELECT 'number of titles updated =', rowCountTitle, 'number of descriptions updated =', rowCountDescription;
END
I know you found a better solution, but I believe the answer to your original question is that you need to SET Done=0; between the two cursors, otherwise the second cursor will only fetch one record before exiting the loop due to Done=1 from the previous handler.
I have finally written a different function that does the same thing:
DROP PROCEDURE IF EXISTS addNewFriend;
DELIMITER //
CREATE PROCEDURE addNewFriend(IN inUserId INT UNSIGNED, IN inFriendEmail VARCHAR(80))
BEGIN
SET #tempFriendId = (SELECT id FROM users WHERE email = inFriendEmail);
SET #tempUsersFriendsUserId = (SELECT user_id FROM users_friends WHERE user_id = inUserId AND friend_id = #tempFriendId);
IF #tempFriendId IS NOT NULL AND #tempUsersFriendsUserId IS NULL THEN
INSERT INTO users_friends (user_id, friend_id) VALUES(inUserId, #tempFriendId);
END IF;
SELECT #tempFriendId as friendId;
END //
DELIMITER ;
I hope this is a better solution, it works fine anyway. Thanks for telling me not to use cursors when not necessary.
Wow, i don't know what to say, please go and read about and learn sql a little, no offense but this is amongst the worst SQL i've ever seem.
SQL is a set based language, cursors, in general, are bad, there are situations when they are usefull, but they are fairly rare. Your use of cursors here is totally inappropriate.
Your logic in the second cursor is also flawed since it will select any record which inludes the friend, not just the required friendship.
If you wanted to fix it you could try giving the second cursor a differant name, but preferably start over.
Set a compound PK or unique constraint on users_friends, then you don't have to worry about checking for a relationship, then try something like this.
INSERT INTO users_friends
SELECT
#inUserId,
users.user_id
FROM
users
WHERE
email = #inFriendEmail
Rather than using cursors to check for the existence of records, you can use the EXISTS clause in the WHERE clause:
INSERT INTO users_friends
(user_id, friend_id)
VALUES
(inUserId, tempFriendId)
WHERE EXISTS(SELECT NULL
FROM users
WHERE email = inFriendEmail)
AND NOT EXISTS(SELECT NULL
FROM users_friends
WHERE user_id = tempFriendId
AND friend_id = tempFriendId);
I made an alteration after reading Paul's comments about the second query, and reversed the logic so the insert won't add duplicates. Ideally this should be handled as a primary key being a compound key (including two or more columns), which would stop the need for checking in code.