Web主要包括两种比较常见的LEFT JOIN方式,一种是正常的LEFT JOIN,也就是只包含ON条件,这种情况没有过滤操作,即左表的数据会全部返回。 另一种方式是有谓词下推,即关 …
Hive SQL查询left join下on条件和where条件区别 - 51CTO
WebMar 31, 2024 · This is easy - left outer join! select * from A left join B on A.idA = B.idB However, what if I need to get v1 = v2 ? I thought that I could just use where. select * from A left join B on A.idA = B.idB where B.id is null or A.v1 = B.v2 Unfortunately, this removes all rows from the left table (A) that did not match any on B (in this example, idA ... Web我可以将dataframe join语句与single on条件一起使用(在pyspark中),但是,如果我尝试添加多个条件,则失败。. 代码:. summary2 = summary.join (county_prop, [ "category_id", "bucket" ], how = "leftouter" ). 上面的代码有效。. 但是,如果我为列表添加其他一些条件,例如summary.bucket ... ecuyer tranchant
SQL中 LEFT JOIN ON 条件的效率高低比较? - 知乎
WebMar 24, 2024 · 在使用left jion时,on和where条件的区别如下: 1、 on条件是在生成临时表时使用的条件,它不管on中的条件是否为真,都会返回左边表中的记录。 2、where条件 … WebJan 8, 2024 · Multiple left outer joins on Hive. Ask Question Asked 4 years, 2 months ago. Modified 4 years, 2 months ago. Viewed 3k times ... And the ON condition works, but it is applied only to the last LEFT join with t_2 subquery, this condition is being checked only to determine which rows to join in the last join, not all joins, it does not affect ... WebJul 12, 2024 · hive中使用join时候on条件 1、如果 select * from a left join b on (a.字段=b.字段) 正常 2、如果 select * from a left join b on (a.字段=b.字段,b.字段=某值,b.……) … ecu worldwide tracking miami