.net - How to set a baud rate to 10400 -
क्या बॉड की दर को 10400 पर सेट करना संभव है? (नेट का प्रयोग करें)
आपको इसकी आवश्यकता नहीं है। मुझ पर विश्वास करो। यहां तक कि अगर आपको लगता है कि आप करते हैं, तो आप नहीं करते।
oracle - The fastest way to check if some records in a database table? -
I have a big table to work with. I have to see that there are some records whose parent_id is equal to my passing value. Currently I do this by implementing "my_table using select count (*) where parent_id =: id"; If the result> 0, it means that they exist. Because this is a very large table, and I do not care what the actual number of records present, I just want to know if it exists, so I think count (*) Bit is disabled. How do I apply this requirement most quickly? I'm using Oracle 10. # Tips for Hibernation & amp; Tricks It suggests writing in such a way: Integer number = (integer) session .createQuery ("Select Count (*) to ...."). UniqueResult (); I do not know what is the magic of the unique rule? Why does it fast? To compare, select "1 from mytable where parent_id = passId and rowrum", which is more efficient? If you are not interested in the number of records, then there is an EXISTS query one: Select 'y'
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