Kevin M. <athlo...@yahoo.com> wrote: > I have a C/C++ application in which I want to store data from a > struct into a table (using SQLite 3.6.23) and later retrieve data > from the table and store it back in the struct. But, I need a > general interface for this as there are many types of structs used. > So, what I have is a function that accepts a pointer to the struct > (ptr), the struct size, and a sqlite3_stmt* variable for the current > row. I then iterate through each column of the row and store the > value retrieved at ptr's address. Then I increment ptr based on the > size of the column. Thus, as long as I store and retrieve columns in > the same order I should be storing the right values in the right > variables for a particular struct instance.
Can't you just store the struct as a blob and be done with it? > However, this method breaks down if a store a 16-bit integer value > like "99" Why is 99 a 16-bit integer value and not, say, an 8-bit or a 32-bit one? How is SQLite supposed to know? > and SQLite stores it internally as an 8-bit value (to save > space) and subsequently retrieves it and gives me a value of 1 for > sqlite3_column_bytes(). sqlite3_column_bytes is really only meaningful for strings and blobs, not for numbers. > This causes alignment issues with the > variables in the struct. So, is there a way I can tell SQLite to > preserve the data size in a particular column? In order to preserve it, you need some way to specify it first. How do you plan to do that? > E.g.: > > CREATE TABLE test ( val1 INTEGER, val2 INT2, val3 INT1 ... ); > > Here val1 is always 4-bytes, val2 is always 2 bytes, and val3 is > always 1 byte. Well, if you want to invent a naming convention like that, why don't you act on it yourself? Retrieve the type name with sqlite3_column_decltype, handle it as you see fit. > I'd prefer a way to do this without having to cast every last column > in a SELECT query to the right size. You can't do that anyway, even if you wanted to. There's no syntax in SQLite that would support that. -- Igor Tandetnik _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
