MySQL 8.0.14 came with Lateral Derived Tables as a new
feature. But what is that and how do you use them?
Let's start what a derived table is. According to the
manual (link below) A derived table is an expression that
generates a table within the scope of a query FROM
clause. You are probably used to using a subquery
or JSON_TABLE where that query feeds data into another
query.
Derived Tables
Derived tables can return a scalar, column, row, or table. But
there are limits to their use.
A derived table cannot be a correlated subquery and a derived
table cannot contain references to other tables of the same
SELECT. And previous to MySQL 8.0.14, a derived table cannot
contain outer references.
Okay, so what is an 'outer reference'? The SQL-92 standard …
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Jan
30
2019
Showing entries 1 to 1