Re: syntax for drop if exists

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От Andrew Dunstan
Тема Re: syntax for drop if exists
Дата
Msg-id 437896F7.2000305@dunslane.net
обсуждение исходный текст
Ответ на Re: syntax for drop if exists  (Tom Lane <tgl@sss.pgh.pa.us>)
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Tom Lane wrote:

>Andrew Dunstan <andrew@dunslane.net> writes:
>  
>
>>The MySQL syntax is actually "drop table if exists foo ...". 
>>Implementing this unfortunately generates a shift/reduce conflict, 
>>    
>>
>
>What did you try exactly?  I don't see any fundamental reason for
>a conflict here.  You may just need to rearrange the grammar to postpone
>the reduction a bit.
>
>  
>

You're right, as usual. I had factored out the IF EXISTS bit into a 
seperate rule. When I undid that and instead used 2 rules for DropStmt, 
the problem disappeared. (This is because it gives bison more info about 
the context of each IF - this has often caught me with bison - I should 
have known better).

cheers

andrew




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