[TYPO3-dev] Should t3lib_db support MySQL's REPLACE INTO statement?

[Steffen Kamper]

Hi Xavier,

Xavier Perseguers schrieb:
> Hi Steffen,
>> Reading the comments in the doc it seems not to be unproblematic, eg 
>> that it makes a delete and the innoDB issues.
>> I also don't understand the difference between REPLACE and INSERT ... 
>> ON DUPLICATE KEY UPDATE, does anyone?
> 
> When you perform a REPLACE on a non existing row, then you INSERT it. 
> Thus it's the same as writing INSERT INTO...
> 
> When you perform a REPLACE on an existing row, you would like instead to 
> perform an UPDATE but MySQL does not bother to check whether the row 
> exists, it DELETEs it then performs an INSERT. This leads to loose all 
> associated data (with constraints and ON DELETE CASCADE statements) 
> whereas you just wanted to UPDATE some row.
> 
> Writing INSERT INTO ... ON DUPLICATE KEY UPDATE means that whenever you 
> try to INSERT a record with a primary key that is already there, instead 
> of having a constraint error, the statement should automatically be 
> converted to an UPDATE statement, which is really nice and I think far 
> better than the original REPLACE statement.
> 

thx for the explanation.

So i would prefer the INSERT_UPDATE method which should be the better 
alternative with same result.

vg Steffen