WHERE子句始终为false,不会命中任何行 9 Impossible WHERE noticed after reading const tables MySQL已经读取了所有const(或system)表,并发现WHERE子句始终为false 10 LooseScan(m..n) 当前使用了半连接LooseScan策略,详见 https://mariadb.com/kb/en/loosescan-strategy/[4] ,翻译 http://www.javacoder.cn/?
用了主键索引或唯一索引的列为查询条件,而它的值是常量时,会用到 const 如果其它的查询条件匹配失败,type 则为null,Extra 列中会有: Impossible WHERE noticed after reading const tables eq_ref: 在联表查询中,对上一个表每一行的组合,从当前表中读取一行,而关联条件的字段用的是主键索引或唯一索引的列,它...
Many teachers I've talked to agree that this form of study really _17I've also seen many of my classmates following my18 and asking for materials with audio recordings to assist in their reading and 19_. So I think people20 that this is the best way to learn various types of ...
system: 只有一条记录的表,这是一种特殊情况 const: 在查询开始时读取,表中最多有一个匹配的行记录,即只读一次,所以非常快 用了主键索引或唯一索引的列为查询条件,而它的值是常量时,会用到 const 如果其它的查询条件匹配失败,type 则为null,Extra 列中会有: Impossible WHERE noticed after reading const tabl...
Or, if reading or listening does the trick, maybe you feel like you’re a verbal learner. We call these labels learning styles. But is there really a way to categorize different types of students? Well, it actually seems that multiple presentation formats, especially if one of them is ...
“The man picked up the car keys and then took the car out of the garage.” “The car keys were picked up by the man and car was taken out of the garage.” 4. Proofreading the Final Text Once all the changes have been made, the last step isproofreading. ...
build_hash_table: Reads the data of the inner table and constructs the execution information of the hash table: total: The total time consumption. fetch: The total time spent reading inner table data. build: The total time spent constructing a hash table. probe: The e...
6. Sri Lanka produces a lot of different types of tea. 7. I started reading, but the changing scenery made it hard to concentrate. 8. I was disappointed with his room, especially considering it cost sixteen dollars a day. 1. seriousness: a state of being serious 2. devotion: great ...
This takes it out of line with natural language, where we routinely subject conditionals to an inferential reading, interpreting ‘if A then B’ to mean that A causes B or otherwise allows us to infer to B in some reasonably reliable way (Douven et al., 2018). Accounts vary in ...
I’ve also seen many of my classmates following my ___ and asking for materials with audio recordings to assist in their reading and ___ . So I think people ___ that this is the best way to learn various types of materials. 【小题1】 A.connect B....