update a set a.zch = (select b.zch from b where b.id = a.id and rownum = 1) where not exists (select 1 from b where b.id = a.id and b.zch = a.zch) and length(a.zch) = 13
更新数据存储过程 CREATE OR REPLACE PROCEDURE update_emp_proc(myempno IN NUMBER,myename IN VARCHAR2) AS BEGIN UPDATE emp SET ename=myename WHERE empno=myempno; END;