Updating database in c friends after dating quotes
That way, a new "note" is inserted of the "note" is changed, and the previous value is returned. The 'work around' suggested in the documentation to obtain the ID of a row updated using the DUPLICATE KEY UPDATE clause of an INSERT statement has a problem in addition to those mentioned by earlier posts.
Namely, if you are using INNODB storage engine and have a FOREIGN KEY referencing the primary key of the table being updated, this strategy may fail with: ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails ....
Doing SELECT and then INSERT is not a complete replacement of INSERT ON DUPLICATE KEY UPDATE: there is a race condition involved.
You will still need to check whether your INSERT works, and if it doesn't then you need to do an update.
Such statements produce a warning in the error log when using statement-based mode and are written to the binary log using the row-based format when using statement against a table having more than one unique or primary key is also marked as unsafe.
When using ON DUPLICATE KEY in combination with a BEFORE INSERT trigger note that if you update a NEW.col_name value in the BEFORE INSERT trigger this will effect the value och values(col_name) in then ON DUPLi CATE KEY UPDATE statement!
Updates to other NEW.col_name in the BEFORE INSERT trigger that is not used in the values(col_name) statement are discarded. 2/b324a/1 If you have an autoincrement pk, and a unique key on say an email address, and the 'on duplicate update' triggers based on the email address, note that the last_insert_id' will NOT be the autoincrement value of the updated row.
In the replacement document, you can omit the field, pass an entirely new document as the second argument to IMongo Collection. When replacing a document, the replacement document must consist of only field/value pairs; i.e. The replacement document can have different fields from the original document.
In the replacement document, you can omit the field, pass an entirely new document as the second argument to replace_one().
My ultimate approach is to not use the DUPLICATE KEY UPDATE for this purpose.