一、原题 View the Exhibit and examine the structure of the PRODUCTS table. You want to display the category with the maximum number of items. You issue the following query: SQL>SELECT COUNT(*), prod_category_id FROM products GROUP BY prod_cate…
今天遇到一个问题,kibana中看到文档数与下面语句查询到的不同
GET /_cat/count/jiankunking_xxxxx_product_expand_test?v
GET /jiankunking_xxxxx_product_expand_test/_search?track_total_hitstrue语句查询结果
epoch timestamp count
1711433785 06:16…
一、原题 Which two statements are true regarding the COUNT function? (Choose two.) A. COUNT(*) returns the number of rows including duplicate rows and rows containing NULL value in any of the columns B. COUNT(cust_id) returns the number of rows including…
在表中数据非常多的时候,如下count语句可能需要数秒时间
select count * from t_goods where xxx
我们可以通过限制count最大数量以提高查询速度,将查询速度控制在毫秒级,sql如下
select count(*) from(
select 1 from t_goods where xxx …
多表联查count数据来进行统计,会出现重复的数据,这时候在查询中加上distinct来返回不同的值.
DB::name(‘member’)
->alias(‘a’)
->field(‘count( distinct b.id) as followCount,count(distinct c.id) as articleCount,count(distinct d.id) as readBookCount,co…
一、原题 View the Exhibit and examine the structure of the SALES table. The following query is written to retrieve all those product ID s from the SALES table that have more than 55000 sold and have been ordered more than 10 times. SQL> SELECT prod_id…
一、原题 Which two statements are true regarding the COUNT function? (Choose two.) A. The COUNT function can be used only for CHAR, VARCHAR2, and NUMBER data types. B. COUNT(*) returns the number of rows including duplicate rows and rows containing NULL …
一、原题 Examine the data in the PROMO_BEGIN_DATE column of the PROMOTIONS table: PROMO_BEGIN _DATE 04-jan-00 10-jan-00 15-dec-99 18-oct-98 22-aug-99 You want to display the number of promotions started in 1999 and 2000. Which query gives the correct outp…
Avg、Count、Max、Min、Sum这些都属于聚合函数,也可以叫分组函数;分组函数:聚合函数对一组数据中的某个要执行计算的列进行返回单一的值。该些聚合函数可以忽略空值,经常与 SELECT语句的 GROUP BY 子句一起使用,因此有…