根据 SQL 中另一个 table 的值从列中提取子字符串

Question

在SQL中（假设ANSI标准SQL），是否可以根据另一个table从一列中提取一个子字符串，并将该子字符串放入另一列？

示例，来自以下 tables：

VISITS
name       summary
---------------------------------------------
john       visit to London
jack       hotel in Paris with park visits
joe        b&b in Paris with ice cream
james      holidays in London and museums
jason      visit in Milan and fashion tour

LOCATIONS
id    name
-------------
1     Paris
2     London
3     Milan
4     Berlin

想法是从summary列中提取位置并输出以下内容：

VISITS
name       summary                              location
---------------------------------------------
john       visit to London                      London
jack       hotel in Paris with park visits      Paris
joe        b&b in Paris with ice cream          Paris
james      holidays in London and museums       London
jason      visit in Milan and fashion tour      Milan

Answer 1

您可以进行模式匹配：

select v.*, l.name
from visits v
left join locations l on v.summary like concat('%', l.name, '%')

正如 jarlh ANSI sql 评论的那样，字符串连接有运算符 ||，因此，取决于您的数据库：

select v.*, l.name
from visits v
left join locations l on v.summary like '%' || l.name || '%'

根据 SQL 中另一个 table 的值从列中提取子字符串

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