Data Import
Filename
The `filename` argument can be used to add an extra `filename` column to the result that indicates which row came from which file. For example:  
```sql
SELECT *
FROM read_csv(['flights1.csv', 'flights2.csv'], union_by_name = true, filename = true);
```  
<div class="narrow_table"></div>  
| FlightDate | OriginCityName |  DestCityName   | UniqueCarrier |   filename   |
|------------|----------------|-----------------|---------------|--------------|
| 1988-01-01 | New York, NY   | Los Angeles, CA | NULL          | flights1.csv |
| 1988-01-02 | New York, NY   | Los Angeles, CA | NULL          | flights1.csv |
| 1988-01-03 | New York, NY   | Los Angeles, CA | AA            | flights2.csv |