select product_id from orders where id = 100 union select product_id from orders where id = 200; 正解: select product_id from orders where id = 100 union all select product_id from orders where id = 200; 原因: union:对两个结果集进行并集操作,不包括重复行,相当于distinct,同时进行默认规则...
[ WITH with_query [, ...] ] SELECT [ ALL | DISTINCT ] select_expr [, ...] [ FROM from_item [, ...] ] [ WHERE condition ] [ GROUP BY [ ALL | DISTINCT ] grouping_element [, ...] ] [ HAVING condition] [ WINDOW window_name AS ( window_definition ) [, ...] ] [ { ...
date：日历日期，包括年（四位），月和日。 time: 一天中的时间，包括小时，分和秒。可以用变量time(...
| Query_ID | Duration | Query || 1 | 0.00035225 | explain select distinct player_id from task limit 20 | | 2 | 1.91772775 | select distinct player_id from task | Query_ID 这个需要就是给show profile for query 具体id来用的。 此时可以看到执行select distinct player_id from task 用了1.9...
SELECT*FROMorders o LEFTJOINusers uONo.user_id=u.idLEFTJOINproducts pONo.product_id=p.idWHEREo.create_time>'2023-01-01'ANDu.vip_level>3ANDp.category_idIN(5,8)ORDERBYo.amountDESCLIMIT1000,20; 使用EXPLAIN关键字查看执行计划的结果如下: ...
The output fromEXPLAINshowsALLin thetypecolumn when MySQL uses afull table scanto resolve a query. 慢SQL 分析与优化 https://mp.weixin.qq.com/s/CaSVhAJgycjjbCxAkII2ZA 从系统设计角度看,一个系统从设计搭建到数据逐步增长,SQL 执行效率可能会出现劣化,为继续支撑业务发展,我们需要对慢 SQL 进行分析和...
tempBuilder = QueryBuilders.rangeQuery("createTime").from(725861532000L, true); boolQueryBuilder .must(tempBuilder); // createTime<=2021-01-01 12:12:12 时间戳 1609474332000L tempBuilder = QueryBuilders.rangeQuery("createTime").to(1609474332000L, true); ...
成功和失败Query趋势 展示所选时间段的成功和失败的Query次数比例,方便了解当前实例的Query整体运行情况。 Query耗时占比趋势 展示所选时间段的Query耗时占比趋势。 默认只分析SELECT、INSERT、UPDATE、DELETE这四类Query的耗时占比情况。 DML趋势 展示DML Query的执行次数趋势。 默认只分析SELECT、INSERT、UPDATE、DELETE...
Copyselect name , dbms_lob.substr(sql_text) sql_text, dbms_lob.substr(hint_text) hint_text, CRTDATE from sysinjecthint where '查询的sql' like CONCAT('%',sql_text,'%')order by crtdate ; 在dmdpc 集群中,由于某些异常,导致执行计划中表行数显示不对,如何解决?
SELECT cp.memory_object_address, cp.objtype, refcounts, usecounts, qs.query_plan_hash, qs.query_hash, qs.plan_handle, qs.sql_handle FROM sys.dm_exec_cached_plans AS cp CROSS APPLY sys.dm_exec_sql_text (cp.plan_handle) CROSS APPLY sys.dm_exec_query_plan (cp.plan_handle) INNER JOI...