You cannot insert a single column, only a full row.
If all your columns int the table allow null, you can use a query like this
INSERT INTO table_name (single_column) VALUES (some_value);
Otherwise you can only update an existing row and this can be done for a single column.
UPDATE table_name SET single_column = some_value WHERE primary_key = a_value;
(Or a natural key)
Maybe do some reading on your own.
SQL Tutorial[
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