簡單SQL操作
阿新 • • 發佈:2017-09-04
rom order cast blog ftime company mpi avg and
以前學SQL的時候,只會簡單的增刪查改,然後什麽課設,畢設都是增刪查改,想想好智障~
1.從表中選取出不同的值
select distinct company from order;
2.返回列的最大值
select MAX(column_name) from table_name;
3.返回某列信息的不同值的最大值
select * from ( select food,max(prince) prince from order group by food )order;
4.周六日的平均氣溫
select AVG(meantempi) from( select * fromweather_date where cast(strftime (‘%w‘,date) as integer) IN (6,0) )weather_date;
5.找出平均氣溫大於55是雨天的平均最低氣溫
select AVG(mintempi) from( select * from weather_data where mintempi > 55 and rain = 1 )weather_data;
簡單SQL操作