<para>
The <literal>CSV</> format has no standard way to distinguish a
<literal>NULL</> value from an empty string.
- <productname>PostgreSQL</>'s <command>COPY</> handles this by
- quoting. A <literal>NULL</> is output as the <literal>NULL</>
- string and is not quoted, while a data value matching the
- <literal>NULL</> string is quoted. Therefore, using the default
- settings, a <literal>NULL</> is written as an unquoted empty
- string, while an empty string is written with double quotes
- (<literal>""</>). Reading values follows similar rules. You can
+ <productname>PostgreSQL</>'s <command>COPY</> handles this using
+ quoting. A <literal>NULL</> is output as an empty string without
+ quotes, while an empty string data value is double-quoted
+ (<literal>""</>). Reading values follows similar rules. You can
use <literal>FORCE NOT NULL</> to prevent <literal>NULL</> input
comparisons for specific columns.
</para>