SQL Join方式总结：（一共7种）
1，内连接
SELECT FROM TABLEA A INNER JOIN TABLEB B ON A.key=B.key
2，全外连接 Mysql暂不支持
SELECT FROM TABLEA A FULL OUTER JOIN TABLEB B ON A.key=B.key
3，全外连接-差集 Mysql暂不支持
SELECT FROM TABLEA A FULL OUTER JOIN TABLEB B ON A.key=B.key WHERE A.key IS NULL OR B.key IS NULL
4，左(外)连接
SELECT FROM TABLEA A LEFT JOIN TABLEB B ON A.key=B.key
5，左(外)连接-左表无连接部分
SELECT FROM TABLEA A LEFT JOIN TABLEB B ON A.key=B.key WHERE B.key IS NULL
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6，右(外)连接
SELECT FROM TABLEA A RIGHT JOIN TABLEB B ON A.key=B.key
7，右(外)连接-右表无连接部分
SELECT FROM TABLEA A RIGHT JOIN TABLEB B ON A.key=B.key WHERE A.key IS NULL