SQL UPDATE 大量更新
MySql, MariaDB
UPDATE A,B SET A.C2=B.C3 WHERE A.C1=B.C1;
MSSQL
UPDATE A SET A.C2=B.C3 FROM A,B WHERE A.C1=B.C1;
参照：http://cuixiaodong214.blog.163.com/blog/static/951639820104100443302/
UPDATE A SET A.C2=B.C3 FROM A JOIN B ON A.C1=B.C1;