Robert Wishlaw wrote:
When .import parses an empty field in the csv file, that is , a comma
immediately followed by another comma, is the cell, in the database,
that corresponds to the empty field a NULL cell?
Robert,
No, it inserts a text field containing an empty string.
All the fields inserted by .import are strings. If they are inserted
into columns with numeric affinity they are converted to numeric values
when stored into the database.
The reason I ask is that when I query the column with
SELECT COUNT(*) FROM table WHERE temp ISNULL;
0 is returned but there are 5 empty cells in that column in the csv file.
This confirms that you don't have any NULL values in that column.
Also when I query
SELECT temp FROM table WHERE temp > 0;
the empty cells are returned as well as the cells containing
temperatures over 0.
This is because you are comparing a numeric value to a string. It's an
empty string, but a string none the less. All strings are greater than
any numeric value (see section 3 Comparison Expressions at
http://www.sqlite.org/datatype3.html for the details of how SQLite
compares values) so in these rows, the empty string is greater than the
literal numeric value of 0.
HTH
Dennis Cote
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