Mysql 使用触发器计算电荷保持为空

我正在尝试使用触发器calculate_费用计算发票中的值，tid和uid已由另一个触发器预设。但在多次调试尝试后，该值仍然为空。一个灵魂能启发我吗

CREATE TABLE temp (tid VARCHAR(10), carparkid VARCHAR(10), time DATETIME, hours INT, minutes INT, per_entry DECIMAL(4,2) DEFAULT '0.00', first_hour DECIMAL(4,2) DEFAULT '0.00', hourly DECIMAL (4,2) DEFAULT '0.00', every_30min DECIMAL (4,2) DEFAULT '0.00', minute DECIMAL (4, 3) DEFAULT '0.00', start_time TIME, end_time TIME);
    CREATE TABLE temp_seq
    (id INT(10) AUTO_INCREMENT, PRIMARY KEY(id));
    DELIMITER //
    DROP TRIGGER IF EXISTS temp_insert;
    CREATE TRIGGER temp_insert
    BEFORE INSERT ON temp
    FOR EACH ROW
    BEGIN
    INSERT INTO temp_seq VALUES (NULL);
    SET NEW.tid = CONCAT('TID', LPAD(LAST_INSERT_ID(), 5, '0'));
    END//
    DELIMITER ;

    DELIMITER //         
    DROP TRIGGER IF EXISTS calculate_charge;
    CREATE TRIGGER `calculate_charge` 
    AFTER INSERT ON temp 
    FOR EACH ROW
    BEGIN 
    UPDATE invoice L 
    SET L.final_charges = NEW.per_entry + NEW.first_hour + ((NEW.hours – 1) * NEW.hourly) + (((NEW.minutes – 60 ) / 30 ) * NEW.every_30min) + (NEW.minutes * NEW.minute)
    WHERE L.tid = NEW.tid;
    END
    //
    DELIMITER ;
CREATE TABLE invoice
(tid VARCHAR(10), userid VARCHAR(10), final_charges DECIMAL(6,2));
CREATE TABLE invoice_seq
(id INT(10) AUTO_INCREMENT, PRIMARY KEY(id));
DELIMITER //
DROP TRIGGER IF EXISTS invoice_insert;
CREATE TRIGGER invoice_insert
BEFORE INSERT ON invoice
FOR EACH ROW
BEGIN
INSERT INTO invoice_seq VALUES (NULL);
SET NEW.tid = CONCAT('TID', LPAD(LAST_INSERT_ID(), 5, '0'));
END//
DELIMITER ;

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Trigger calculate\u charge不符合语法。我无法获取此so语法，因为减号不是减号。它符合语法吗？。Trigger calculate\u charge不符合语法。我无法获取此so语法，因为减号不是减号。它符合语法吗？。

MariaDB [carparkful]> select*from invoice;
+----------+----------+---------------+
| tid      | userid   | final_charges |
+----------+----------+---------------+
| TID00001 | UID00003 |          NULL |
| TID00002 | UID00002 |          NULL |
| TID00003 | UID00001 |          NULL |
+----------+----------+---------------+
3 rows in set (0.00 sec)