Can't update table 'Donor' in stored function/trigger because it is already used by statement which invoked this stored function/trigger

Question

I am trying to insert the data into the database but it keeps saying

Can't update table 'Donor' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.

This is my sql file

SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET AUTOCOMMIT = 0;
START TRANSACTION;
SET time_zone = "+00:00";



--
-- Table Site
--

CREATE TABLE `Site`(
  `sid` int(50) NOT NULL PRIMARY KEY,
  `sname` varchar(50) NOT NULL,
  `saddr` varchar(50) NOT NULL
);


--
-- Table Hospital
--

CREATE TABLE `Hospital` (
  `hid` int(50) NOT NULL PRIMARY KEY,
  `hname` varchar(50) NOT NULL,
  `haddr` varchar(100) NOT NULL,
  `hcontact` varchar(20) NOT NULL
);


--
-- Table Organization
--

CREATE TABLE `Organization` (
  `oid` int(50) NOT NULL PRIMARY KEY,
  `oname` varchar(50) NOT NULL,
  `oaddr` varchar(100) NOT NULL,
  `ocontact` varchar(20) NOT NULL
);


--
-- Table Donor
--

CREATE TABLE `Donor`(
  `did` int(50) NOT NULL PRIMARY KEY,
  `oid` int(50) NOT NULL,
  `dname` varchar(50) NOT NULL,
  `dblood` varchar(50) NOT NULL,
  `dage` int(50) NOT NULL,
  `dsex` char(10) NOT NULL,
  `dmail` varchar(50) NOT NULL UNIQUE,
  `dcount` int(40) NOT NULL,
  CONSTRAINT FK_Organization FOREIGN KEY (`oid`) REFERENCES `Organization`(`oid`),
  CONSTRAINT CHK_PersonAge CHECK (`dage`>=17 and `dage` < 80)
);


--
-- Table Volunteer  : Is a weak entity 
-- 

CREATE TABLE `Volunteer`(
  `vid` int(50) NOT NULL,
  `hid` int(50) NOT NULL,
  `vname` varchar(50) NOT NULL,
  PRIMARY KEY(`vid`, `hid`),
  CONSTRAINT FK_Hospital FOREIGN KEY (`hid`) REFERENCES `Hospital`(`hid`)

);



--
-- Table Donation
--

CREATE TABLE `Donation`(
  `did` int(50) NOT NULL,
  `vid` int(50) NOT NULL,
  `hid` int(50) NOT NULL,  
  `sid` int(50) NOT NULL,
  `date` DATE NOT NULL, -- YYYY-MM-DD format
  PRIMARY KEY(`did`, `date`),
  CONSTRAINT FK_Donor FOREIGN KEY (`did`) REFERENCES `Donor`(`did`),
  CONSTRAINT FK_VolunteerPresence FOREIGN KEY (`vid`,`hid`) REFERENCES `Volunteer`(`vid`,`hid`),
  CONSTRAINT FK_Site FOREIGN KEY (`sid`) REFERENCES `Site`(`sid`)
);


-- Triggers

-- Make dcount 0 if anything else entered

DELIMITER $$

CREATE TRIGGER `Donation_Count`
AFTER INSERT
ON `Donor` FOR EACH ROW
BEGIN
  UPDATE `Donor` SET `dcount` = 0 WHERE `did` = NEW.did;
END$$

DELIMITER ;

COMMIT;

For the very first INSERT query it returns the error. The query is of the form

INSERT INTO Donor VALUES(1,1, 'Clint Barton', 'B+', 45, 'Male', 'hawkeye@gmail.com',0);

Could someone explain why exactly is this happening. I checked for duplication of a trigger but there were none. Any kind of help would be appreciated.

Answer 1

This answer helped me. Then I used the same knowledge to fix the issue using the trigger

DELIMITER $$

CREATE TRIGGER `Donation_Count`
BEFORE INSERT
ON `Donor` FOR EACH ROW
BEGIN
  SET NEW.dcount = 0;
END$$

DELIMITER ;