Handle SQL NULL Values in CSV Output

NULL Values — From SQL to CSV

SQL NULL represents the absence of a value, but CSV has no native concept of null. When converting SQL to CSV, you need to decide how to represent missing data. The tool offers four options.

Example SQL

CREATE TABLE contacts (
  id INTEGER PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  phone VARCHAR(20),
  fax VARCHAR(20),
  notes TEXT
);

INSERT INTO contacts VALUES
  (1, 'Alice', '+1-555-0100', NULL, 'Primary contact'),
  (2, 'Bob', NULL, NULL, NULL),
  (3, 'Charlie', '+1-555-0102', '+1-555-0103', NULL);

Output with Different NULL Settings

Empty string (default):

id,name,phone,fax,notes
1,Alice,+1-555-0100,,Primary contact
2,Bob,,,
3,Charlie,+1-555-0102,+1-555-0103,

NULL literal:

id,name,phone,fax,notes
1,Alice,+1-555-0100,NULL,Primary contact
2,Bob,NULL,NULL,NULL
3,Charlie,+1-555-0102,+1-555-0103,NULL

Which Option to Choose

Setting	Best For
Empty string	Spreadsheets (Excel, Google Sheets)
NULL	Preserving SQL semantics for reimport
null	JSON-style downstream tools
N/A	Human-readable reports

The preview table italicizes NULL representations so you can visually distinguish them from actual empty string values in the data.