mysql语句之汇总语句和分组数据

1.SELECT AVG(prod_price) AS avg_price
FROM table_name;

取prod_price列的平均值输出。

2.SELECT AVG(DISTINCT prod_price) AS avg_price
FROM table_name;

取prod_price列中的不同值计算平均值输出。

3.SELECT COUNT(*) AS num_items,
MIN(prod_price) AS price_min,
MAX(prod_price) AS price_max,
AVG(prod_price) AS price_avg
FROM table_name;

组合使用聚集函数，输出四个相应的计算后的值。

4.SELECT vend_id,COUNT(*) AS num_prods
FROM table_name
GROUP BY vend_id;

GROUP BY子句指示mysql按vend_id排序并分组数据。

5.SELECT cust_id,COUNT(*) AS orders
FROM table_name
GROUP BY cust_id
HAVING COUNT(*)>=2;

HAVING 起着过滤分组的作用。