1) NI is working on a white paper that walks you through the decision of which file format / database is best in your use case. I cannot tell for sure when it is going to be available on ni.com.
2) DIAdem can readily access the "Citadel" databases coming with LabVIEW DSC or VI Logger. Citadel is a streaming database designed for data logging with high data throughput and low disk footprint. It is not as flexible as a commercial SQL database when it comes to storing complex descriptive data like testcell setups, test step definitions etc. It doesn't seem that you are storing such complex data, so from what I can tell from your description, Citadel should fit your needs. In case you need SQL connectivity, NI provides an ODBC driver for Citadel data. 3) DIAdem has a native command set for SQL/ODBC data access and supports ADO via VBScript - both of which need writing DIAdem autosequences. DIAdem also comes with an SQL table reader that allows you to interactively import complete database columns into DIAdem channels (no queries). The database connectivity toolkit provides programmatic access to databases from LabVIEW, but it doesn't match the comprehensive feature set (data viewer etc.) you find in LabVIEW DSC. 4) Storing measured values to SQL databases requires some design consideration. Unless you are dealing with very small amounts of measured data, you will probably need to separate the "meta"-data you use for searching (test description, input values etc) from the actual measured data values. You then store the meta data to database cells you can query via SQL. The measured data values are stored as binary blocks to "BLOB"-cells (binary large objects). This is done for performance and disk-space reasons. Only if you need to perform SQL queries on all of your actual measured values, it makes sense to store them in single database cells. Another way of storing measured data is to write the data to binary files, and copy the meta-data from the files into a database for searching. That allows you to use a low-end database for huge amounts of data - but you need to take care of keeping your database in sync with your files. There is also a couple of higher-end solutions around (ASAM-ODS standard, VARRAYs on ORACLE systems ...) that can be accessed with NI software, but it sounds like you can get the job done with something more basic.
