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SELECT store_name,SUM(sales) FROM Store_Information GROUP BY store_name HAVING SUM(salse)>1500 |
SELECT COUNT(store_name) FROM Store_Information WHERE store_name is not NULL |
SELECT store_name FROM Store_Information WHERE Sales>1000 |
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HAVING是对函数产生的值来设定条件 |
WHERE是对函数的变量来设定条件 |
WHERE给出的是SELECT的条件，即选择栏位的条件，这个条件一般是由某个栏位名来表达、决定 |