[TOC=1,5] >[success] # 聚集函数 >在应用中，经常需要汇总数据而不用把它们实际检索处理，MySQL 提供了专 门的聚集操作函数，如下图所示：  <br> >[danger] ##### 返回平均值 - AVG `SELECT AVG(prod_price) AS avg_price FROM products;`  **注：** 配合where 条件计算 `SELECT AVG(prod_price) AS avg_price FROM products WHERE vend_id=1003;`  * * * * * <br> >[danger] ##### 返回列的行数 - count `SELECT COUNT(*) AS num_cust FROM products;`  * * * * * <br> >[danger] ##### 返回最大值 - max `SELECT MAX(prod_price) AS max_price FROM products;`  **注：用limit** `SELECT prod_price AS max_price FROM products ORDER BY prod_price DESC LIMIT 1;` * * * * * <br> >[danger] ##### 返回最小值 - min `SELECT min(prod_price) AS max_price FROM products;` * * * * * <br> >[danger] ##### 返回和 - sum `SELECT SUM(prod_price) AS max_price FROM products;;`  * * * * * <br> >[danger] ##### 将几个函数组合使用