WebMar 30, 2024 · left join on +多条件与where区别 重点 先匹配,再筛选where条件。 本文将通过几个例子说明两者的差别。 表1:product 表2:product_details 1. 单个条件 select * … Web嵌套语句. case when 也可以进行嵌套组合,有了上述标准语法做基础,嵌套写法不难理解。. 这里以女子是否选择相亲的决策树为例:. select CASE WHEN age<30 THEN CASE WHEN look = 'handsome' OR look = 'normal' THEN CASE WHEN salary = 'high' THEN 'meeting' WHEN salary = 'low' THEN 'no meeting' ELSE CASE ...
LanguageManual Joins - Apache Hive - Apache Software …
WebDec 14, 2024 · 一、join与left join的全称. JOIN是INNER JOIN的简写,LEFT JOIN是LEFT OUTER JOIN的简写。 二、join与left join的应用场景. JOIN一般用于A表和B表都存在的 … WebApache Hive Join – HiveQL Select Joins Query. Basically, for combining specific fields from two tables by using values common to each one we use Hive JOIN clause. In other words, to combine records from two or more tables in the database we use JOIN clause. However, it is more or less similar to SQL JOIN. Also, we use it to combine rows from ... shanice beerepoot
hive关于left join 和join时候on条件总结 - CSDN博客
WebSep 1, 2016 · 1. All rows are returned FROM table1 when you use a left join even if there is no match in table2. But an inner join REQUIRES A MATCH from both tables, so you get less rows from the first query and more rows in the second query. This behaviour is not specific to HIVE by the way. – Paul Maxwell. WebFeb 4, 2024 · Just like in most, if not all, databases, the outer word is optional in left [outer] join, while both syntaxs have the exact same meaning.. A quick glance at the hive documentation:. Hive supports the following syntax for joining tables: join_table: table_reference [INNER] JOIN table_factor [join_condition] table_reference … WebThe HiveQL LEFT OUTER JOIN returns all the rows from the left table, even if there are no matches in the right table. This means, if the ON clause matches 0 (zero) records in the … shanice beckford-norton