http://www.sqlite.org/datatype3.html

http://*.com/questions/7337882/what-is-the-difference-between-sqlite-integer-data-types-like-int-integer-bigi

微软的So in MS Sql Server (for example), an "int" == "integer" == 4 bytes/32 bits.
In contrast, a SqlLite "integer" can hold whatever you put into it: from a 1-byte char to an 8-byte long long.

http://*.com/questions/1171196/what-is-the-difference-between-varchar-and-varchar2

As for now, they are synonyms.

VARCHAR is reserved by Oracle to support distinction between NULL and empty string in future, as ANSI standard prescribes.

VARCHAR2 does not distinguish between a NULL and empty string, and never will.

If you rely on empty string and NULL being the same thing, you should use VARCHAR2.