CROSS JOIN 与 LATERAL JOIN 在 PostgreSQL 中的结合使用是可能的,但通常不常见,因为 CROSS JOIN 本身就是笛卡尔积,而 LATERAL JOIN 允许子查询引用外部查询的列。 在PostgreSQL 中,CROSS JOIN 和LATERAL JOIN 是两种不同的连接类型,它们有不同的用途和行为。 CROSS JOIN: 定义:CROSS JOIN 返回两个表的笛卡尔积...
它和Lateral Join的原理和用法基本上是一样的。 1.1 核心概念 CROSS APPLY:类似于INNER JOIN,它将左侧表的每一行与右侧表值函数或子查询的结果进行关联。如果右侧没有匹配的结果,左侧的行将被过滤掉。 OUTER APPLY:类似于LEFT OUTER JOIN,它将左侧表的每一行与右侧表值函数或子查询的结果进行关联。即使右侧没有匹...
它和Lateral Join的原理和用法基本上是一样的。 1.1 核心概念 CROSS APPLY:类似于INNER JOIN,它将左侧表的每一行与右侧表值函数或子查询的结果进行关联。如果右侧没有匹配的结果,左侧的行将被过滤掉。 OUTER APPLY:类似于LEFT OUTER JOIN,它将左侧表的每一行与右侧表值函数或子查询的结果进行关联。即使右侧没有...
It’s called LATERAL JOIN there. I ran this example on Postgres (9.4) and it pretty much shows the same behavior with the exception that the first query is really, really slow on Postgres (12 minutes with just 25.000 rows instead of 100.000). But the difference between the version with...
-- MySQL、PostgreSQL 以及 SQLiteSELECT s.sale_year, s.sale_month, e.emp_name, s.amountFROM emp_sales sJOIN employee e ON (e.emp_id = s.emp_id)WHERE s.sale_year = 2021AND s.sale_month = 1ORDER BY s.amount DESCLIMIT 1;-- Oracle 和 SQL Server...
The Cross Apply and Outer Apply features are not available in MySQL or PostgreSQL. A feature called Lateral Joins, which is similar, was introduced in MySQL 8.0.14 and PostgreSQL 9.0. What is a Table-Valued Function? To understand how Cross Apply and Outer Apply work, and why they are nee...