copy null data(tsv/csv) into postgresql

copy_csv

postgres=# copy t(id, name) from '/tmp/data.csv' (format csv) ;
COPY 5
postgres=# select id , name, length(name) from t;
 id |  name  | length
----+--------+--------
  1 | food   |      4
  2 | energy |      6
  3 | ''     |      2
  4 |        |      0
  5 |        |
(5 rows)

copy_csv_force_not_null

postgres=# copy t(id, name) from '/tmp/data.csv' (format csv, force_not_null(name)) ;
COPY 5
postgres=# select id , name, length(name) from t;
 id |  name  | length
----+--------+--------
  1 | food   |      4
  2 | energy |      6
  3 | ''     |      2
  4 |        |      0
  5 |        |      0
(5 rows)

copy_syntax.sql

COPY table_name [ ( column_name [, ...] ) ]
    FROM { 'filename' | STDIN }
    [ [ WITH ] ( option [, ...] ) ]

copy_tsv

postgres=# copy t(id, name) from '/tmp/data.tsv';
COPY 4
postgres=# select id , name, length(name) from t;
 id |  name  | length
----+--------+--------
  1 | food   |      4
  2 | energy |      6
  3 |        |      0
  4 |        |
(4 rows)

copy_tsv_with_null

postgres=# copy t(id, name) from '/tmp/data.tsv' (null '');
COPY 4
postgres=# select id , name, length(name) from t;
 id |  name  | length
----+--------+--------
  1 | food   |      4
  2 | energy |      6
  3 |        |
  4 | N      |      1
(4 rows)

create_table.sql

create table t(
    id integer,
    name text

);

postgres=# \d t
       Table "public.t"
 Column |  Type   | Modifiers
--------+---------+-----------
 id     | integer |
 name   | text    |

dat.tsv

1    food
2	energy
3	
4	\N

data.csv