MySQL triggers to update field based on sum of column from another table

问题

I have two tables 'survey' and 'results'

survey table
-----------------------------------------------
survey_id  | name  | p1q1 | p1q2 | p1q5  
-----------------------------------------------
1          | John  | 10   | 10   | 5 
-----------------------------------------------
2          | Erick | 12   | 15   | 23 
-----------------------------------------------

results table

id  | Uptake | PY5Q1 |
----------------------------
1   | AZT    | NULL  |
----------------------------
2   | UPDP   | NULL  |
----------------------------

I'm new to triggers and am trying to figure out how to get sum of p1q5 in survey table and update it to PY5Q1 where id = 1 in results table Any ideas will be appreciated

CREATE TRIGGER `results` AFTER INSERT ON `survey` FOR EACH ROW BEGIN
UPDATE results SET PY5Q1=(SELECT SUM(p1q5)) WHERE id=1;
END

回答1:

CREATE TRIGGER `results` AFTER INSERT ON `survey` FOR EACH ROW
BEGIN
UPDATE results SET PY5Q1=(SELECT SUM(p1q5)FROM survey) WHERE id=1;
END

来源：https://stackoverflow.com/questions/28579734/mysql-triggers-to-update-field-based-on-sum-of-column-from-another-table