Standard for PostgreSQL for string imput values is using apostrophe (‘), not quotation mark (“). Quotation marks are used when addressing table columns.
Empty values should be processed differently (I have experienced problems when inserting values where a string parameter was “” - had to manually change to null).
Also, allow user to specify his primary key and column constraints (at least the simple ones) (this one is not an important upgrade).
Special handling of certain characters in string values (Suggestion: apostrophes and quotation marks found in string values could be replaced with ' and ", respectively. Maybe allow user to specify a way to handle that kind of input?)