1. MySQL can be added, deleted and modified directly, and Oracle needs commit;
2. groupby. If you use groupby under oracle, the fields after groupby must appear after select, otherwise an error will be reported, but mysql will not;
3. MySQL uses the concat() function to connect strings. Oracle not only has the concat() function, but also can use ||;
4. MySQL uses elseif for judgment, and oracle uses Elsif;
5. MySQL paging uses limit, and Oracle paging requires the help of rownum keyword;
6. MySQL can have no from, oracle must have it, and can be written as fromdual;
7. MySQL directly writes loop judgment statements, and oracle must use PLSQL statements;
8. MySQL automatically grows auto_increment, and oracle uses sequence instead;
9. MySQL does not have full external connections, so it uses collection connection instead. Oracle has full external connections, and the left and right external connections have its own syntax: (+);