Case Description:
Enter the code by the book
CREATE TRIGGER newproduct AFTER INSERT ON products
FOR EACH ROW SELECT 'Product added'//
Error Not allowed to return a result set from a trigger
Find a reason: after MYSQL5, does not allow the trigger to return any results, so use into @ variable name, will assign the result to a variable, you can use the select call
change into
CREATE TRIGGER newproduct AFTER INSERT ON products
FOR EACH ROW SELECT 'Product added' INTO @ asd // # variable name with the @ # DELIMITER // will guide sentence end symbol; // amended as
success!
Take a look at the variables so what?
SELECT @asd//
Had nothing, not insertion operation, so no value is displayed!
Insert a row in the products table: Tips, note that the data type of each column of data is inserted, and ensure that the data is not the primary key column is repeated
Then run the SELECT @ asd //
Now with!
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