Re: [SQL] behavior of ' = NULL' vs. MySQL vs. Standards
От | Thomas Lockhart |
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Тема | Re: [SQL] behavior of ' = NULL' vs. MySQL vs. Standards |
Дата | |
Msg-id | 3B1F848C.CAA0F438@fourpalms.org обсуждение исходный текст |
Ответ на | Re: [SQL] behavior of ' = NULL' vs. MySQL vs. Standards (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
> > Yes, column = NULL should *never* return true according to the spec (it > > should always return NULL in fact as stated). The reason for breaking > > with the spec is AFAIK to work with broken microsoft clients that seem to > > think that =NULL is a meaningful test and generate queries using that. > Microsoft Access is the guilty party, IIRC. I recently tried to stir up > some interest in changing this behavior back to the standard, but > apparently there are still too many people using broken versions of > Access. Since according to the standard "column = NULL" is a near-useless construct (equivalent to "FALSE") it does not seem to pollute the grammar much to allow an M$ compatible interpretation. I was not happy having it added (much better to ask that responsive, customer-focused company to fix their language compliance) but now that it is there it seems to be an isolated and manageable feature. - Thomas
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