I'm not 100% sure what is being done here, but a cursory glance makes it clear your escaping is not correct or at least, not consistent.
Try this and see if it works:
```c++
const char * sql =
"CREATE VIRTUAL TABLE csv_tab USING "
"csv(header = True, filename = 'c:/tab.csv', "
"schema = 'CREATE TABLE csv_schema ("
"some_date DATE NOT NULL,"
"some_str1 TEXT COLLATE BINARY DEFAULT '''',"
"some_str2 TEXT COLLATE BINARY DEFAULT '''',"
"some_flt DOUBLE"
"); ');";
```