I have a very common usage pattern for converting the output of a database query (LibPQ for example)
So something like
data = DataFrame(LibPQ.execute(pgconnection, "select column1,column2 from table1 where condition1 = true"))
This generally works quite well, except where the result of the query returns 0 rows. In that case, the schema of the resulting dataframe is not consistent with the schema of the dataframe when there are rows returned from the query
It gets returned like this
0×2 DataFrame Row │ schema data │ CursorSc… Array… ─────┴───────────────────
if I want the value of column1, I get an error since that column doesn’t exist in the 0 row dataframe.
Is there a way to get the output of this query to always have the same DataFrame schema in all cases regardless of query output?
Otherwise, I always have to create a temporary dataframe and check the size before proceding to the next step.