"LIMIT %%limit int%%" in MySQL

[ras0q]

ref: #123

In #123, you mentioned that it is impossible to use LIMIT %%limit int%% (same for OFFSET %%offset int%%) on MySQL, can you fix it in the following way? Maybe these methods involve breaking changes.

• Change the regular expression in ParseQueryFields to, for example, [^%]+%%[^%]+%% so that LIMIT %%limit int%% can be detected
• Replace LIMIT in introspection query's nth with 0 instead of NULL when LIMIT is forward
• Add a syntax like %%limit int,as_limit%%
• and so on...