Re: [sqlite] Selecting NULL
On 7/11/2012 2:00 PM, deltagam...@gmx.net wrote: If mydetails contains a value, and I delete this value with "SQLite Database Browser" it seems not to be a "real NULL", has someone an explanation for this behaviour ? The tool probably sets the field to an empty string, which is not the same as null. -- Igor Tandetnik ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Selecting NULL
On Wed, Jul 11, 2012 at 2:00 PM, deltagam...@gmx.net wrote: > If mydetails contains a value, and I delete this value with "SQLite Database > Browser" > it seems not to be a "real NULL", has someone an explanation for this > behaviour ? It depends on your meaning of word "delete". But maybe when you clear the value in SQLite Database Browser it writes empty string? Pavel ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Selecting NULL
Am 11.07.2012 19:45, schrieb Pavel Ivanov: // here maybe NULL is returned ? mydetails = (char*)sqlite3_column_text(stmt, 0 ); Check sqlite3_column_type() before calling sqlite3_column_text(). If it returns SQLITE_NULL then you have NULL. Pavel On Wed, Jul 11, 2012 at 1:40 PM, deltagam...@gmx.net wrote: Hello, how to process if the select-statement selects a column with NULL ? == char *mydetails; char *sql; sqlite3_stmt *stmt; sqlite3 *db; const char dbname[] = "mysqlite.db"; sql = "Select mydetails from mytable"; rc = sqlite3_prepare(db, sql, strlen(sql), &stmt, NULL); rc = sqlite3_step(stmt); while(rc == SQLITE_ROW) { // here maybe NULL is returned ? mydetails = (char*)sqlite3_column_text(stmt, 0 ); rc = sqlite3_step(stmt); } === ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users Pavel, thanks a lot. If mydetails contains a value, and I delete this value with "SQLite Database Browser" it seems not to be a "real NULL", has someone an explanation for this behaviour ? ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Selecting NULL
> // here maybe NULL is returned ? > mydetails = (char*)sqlite3_column_text(stmt, 0 ); Check sqlite3_column_type() before calling sqlite3_column_text(). If it returns SQLITE_NULL then you have NULL. Pavel On Wed, Jul 11, 2012 at 1:40 PM, deltagam...@gmx.net wrote: > Hello, > > how to process if the select-statement selects a column with NULL ? > > > == > char *mydetails; > char *sql; > sqlite3_stmt *stmt; > sqlite3 *db; > const char dbname[] = "mysqlite.db"; > > > sql = "Select mydetails from mytable"; > > rc = sqlite3_prepare(db, sql, strlen(sql), &stmt, NULL); > > rc = sqlite3_step(stmt); > > > while(rc == SQLITE_ROW) { > > // here maybe NULL is returned ? > mydetails = (char*)sqlite3_column_text(stmt, 0 ); > rc = sqlite3_step(stmt); > } > === > ___ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] Selecting NULL
Hello, how to process if the select-statement selects a column with NULL ? == char *mydetails; char *sql; sqlite3_stmt *stmt; sqlite3 *db; const char dbname[] = "mysqlite.db"; sql = "Select mydetails from mytable"; rc = sqlite3_prepare(db, sql, strlen(sql), &stmt, NULL); rc = sqlite3_step(stmt); while(rc == SQLITE_ROW) { // here maybe NULL is returned ? mydetails = (char*)sqlite3_column_text(stmt, 0 ); rc = sqlite3_step(stmt); } === ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users