为什么MySQL在FULL OUTER JOIN上报语法错误?
SELECT airline, airports.icao_code, continent, country, province, city, website
FROM airlines
FULL OUTER JOIN airports ON airlines.iaco_code = airports.iaco_code
FULL OUTER JOIN cities ON airports.city_id = cities.city_id
FULL OUTER JOIN provinces ON cities.province_id = provinces.province_id
FULL OUTER JOIN countries ON cities.country_id = countries.country_id
FULL OUTER JOIN continents ON countries.continent_id = continents.continent_id
它说
您的 SQL 语法有错误;检查与您的 MySQL 服务器版本相对应的手册,了解在airlines.iaco_code = airports.iaco_code 上的'outer join airports
附近使用的正确语法第 4 行的全外连接
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'outer join
airports
on airlines.iaco_code = airports.iaco_code full outer join' at line 4
语法在我看来是正确的.我以前从来没有做过很多连接,但我需要一个表中的那些列,这些列被各种 id 交叉引用.
The syntax looks right to me. I've never done a lot of joins before, but I need those columns in a table which is cross referenced by various id's.
推荐答案
MySQL 中没有 FULL OUTER JOIN
.请参阅 7.2.12.外连接简化和12.2.8.1.JOIN 语法:
There is no FULL OUTER JOIN
in MySQL. See 7.2.12. Outer Join Simplification and 12.2.8.1. JOIN Syntax:
你可以模拟 FULL OUTER JOIN
使用UNION(从 MySQL 4.0.0 开始):
You can emulate
FULL OUTER JOIN
using UNION (from MySQL 4.0.0 on):
有两个表 t1, t2:
with two tables t1, t2:
SELECT * FROM t1
LEFT JOIN t2 ON t1.id = t2.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
三个表 t1、t2、t3:
with three tables t1, t2, t3:
SELECT * FROM t1
LEFT JOIN t2 ON t1.id = t2.id
LEFT JOIN t3 ON t2.id = t3.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
LEFT JOIN t3 ON t2.id = t3.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
RIGHT JOIN t3 ON t2.id = t3.id
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