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I find many times people use temporary tables because they learned in other databases that joining too many tables in a single query is a ʹbad thingʹ. This is a practice that must be unlearned for Oracle development. Rather then trying to out‐smart the optimizer and breaking what should be a single query into three or four queries that store their sub results into temporary tables and then joining the temporary tables, you should just code a single query that answers the original question. Referencing many tables in a single query is OK; the temporary table crutch is not needed in Oracle for this purpose.

extract expert one-on-one oracle P.321

posted on 2010-04-19 21:28  mzwang123  阅读(119)  评论(0)    收藏  举报