Overriding unique indexed values
This is what I'开发者_如何学JAVAm doing right now (name
is UNIQUE
):
SELECT * FROM fruits WHERE name='apple';
Check if the query returned any result. If yes, don't do anything. If no, a new value has to be inserted:
INSERT INTO fruits (name) VALUES ('apple');
Instead of the above is it ok to insert the value into the table without checking if it already exists? If the name already exists in the table, an error will be thrown and if it doesn't, a new record will be inserted.
Right now I am having to insert 500 records in a for loop, which results in 1000 queries. Will it be ok to skip the "already-exists" check?
You can use the IGNORE feature:
INSERT IGNORE INTO fruits VALUES ('apple')
If there is a key violation, it just skips this value
check out
INSERT IGNORE INTO ...
and
INSERT ON DUPLICATE KEY UPDATE ...
Thes second method is preferred as the IGNORE statement simply causes mysql to issue warning instead of error
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