What would be the best way to integrate WDQS with the tabular data, as well as other CSV sources? For example, if a large dataset provider publishes CSV or TSV files, and WDQS wants to federate with it, we could do something like this (this example should be modified as we flash out the exact interface)
```lang=sparql
SELECT * WHERE {
# This is a well known public data source for stock quotes - Tesla daily, first lines:
# Date Open High Low Close Volume Ex-Dividend Split Ratio Adj. Open Adj. High Adj. Low Adj. Close Adj. Volume
# 2017-11-24 313.79 316.41 311 315.55 3242220 0 1 313.79 316.41 311 315.55 3242220
SERVICE <https://www.quandl.com/api/v3/datasets/WIKI/TSLA.csv> {
# Some way of column parsing is TBD. Here we extract two columns, and we filter by date
# The prefix for the first column could be something else
bd:Date bd:serviceParam ?date . # output to ?date
bd:Date bd:serviceParamType 'date:yyyy-mm-dd' . # date parsing
bd:Close bd:serviceParam ?close .
bd:Close bd:serviceParamType 'double' .
}
# Extract a single date/close value
FILTER ( ?date = "2017-11-24T00:00:00Z"^^xsd:dateTime )
}
```
Expected result:
| ?date | ?close |
| 2017-11-24 | 315.55 |