聚合函数

-- 聚合查询
SELECT city, max(temp_lo)
FROM weather
WHERE city LIKE 'S%'
GROUP BY city
HAVING max(temp_lo) < 40; -- HAVING 子句始终包含聚合函数, 否则没有意义

　

更新语句

-- 更新语句
UPDATE weather
    SET temp_hi = temp_hi - 2,  temp_lo = temp_lo - 2
    WHERE date > '1994-11-28';

 

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