Nsryjdtyk

I'm running PostgreSQL 9.2.6 on OS X 10.6.8. I would like to import data from a CSV file with column headers into a database. I can do this with the COPY statement, but only if I first manually create a table with a column for each column in the CSV file. Is there any way to automatically create this table based on the headers in the CSV file?

Per this question I have tried

COPY test FROM '/path/to/test.csv' CSV HEADER;

But I just get this error:

ERROR: relation "test" does not exist

And if I first create a table with no columns:

CREATE TABLE test ();

I get:

ERROR: extra data after last expected column

I can't find anything in the PostgreSQL COPY documentation about automatically creating a table. Is there some other way to automatically create a table from a CSV file with headers?

You can't find anything in the COPY documentation, because COPY cannot create a table for you.

You need to do that before you can COPY to it.

There is a very good tool that imports tables into Postgres from a csv file.
It is a command-line tool called pgfutter (with binaries for windows, linux, etc.). One of its big advantages is that it recognizes the attribute/column names as well.

The usage of the tool is simple. For example if you'd like to import myCSVfile.csv:

pgfutter --db "myDatabase" --port "5432" --user "postgres" --pw "mySecretPassword" csv myCSVfile.csv

This will create a table (called myCSVfile) with the column names taken from the csv file's header. Additionally the data types will be identified from the existing data.

A few notes: The command pgfutter varies depending on the binary you use, e.g. it could be pgfutter_windows_amd64.exe (rename it if you intend to use this command frequently). The above command has to be executed in a command line window (e.g. in Windows run cmd and ensure pgfutter is accessible). If you'd like to have a different table name add --table "myTable"; to select a particular database schema us --schema "mySchema". In case you are accessing an external database use --host "myHostDomain".

A more elaborate example of pgfutter to import myFile into myTable is this one:

pgfutter --host "localhost" --port "5432" --db "myDB" --schema "public" --table "myTable" --user "postgres" --pw "myPwd" csv myFile.csv

Most likely you will change a few data types (from text to numeric) after the import:

alter table myTable

  alter column myColumn type numeric

    using (trim(myColumn)::numeric)

There is a second approach, which I found here (from mmatt). Basically you call a function within Postgres (last argument specifies the number of columns).

select load_csv_file('myTable','C:/MyPath/MyFile.csv',24)

Here is mmatt's function code, which I had to modify slightly, because I am working on the public schema. (copy&paste into PgAdmin SQL Editor and run it to create the function)

CREATE OR REPLACE FUNCTION load_csv_file(

    target_table text,

    csv_path text,

    col_count integer)

  RETURNS void AS

$BODY$



declare



iter integer; -- dummy integer to iterate columns with

col text; -- variable to keep the column name at each iteration

col_first text; -- first column name, e.g., top left corner on a csv file or spreadsheet



begin

    set schema 'public';



    create table temp_table ();



    -- add just enough number of columns

    for iter in 1..col_count

    loop

        execute format('alter table temp_table add column col_%s text;', iter);

    end loop;



    -- copy the data from csv file

    execute format('copy temp_table from %L with delimiter '','' quote ''"'' csv ', csv_path);



    iter := 1;

    col_first := (select col_1 from temp_table limit 1);



    -- update the column names based on the first row which has the column names

    for col in execute format('select unnest(string_to_array(trim(temp_table::text, ''()''), '','')) from temp_table where col_1 = %L', col_first)

    loop

        execute format('alter table temp_table rename column col_%s to %s', iter, col);

        iter := iter + 1;

    end loop;



    -- delete the columns row

    execute format('delete from temp_table where %s = %L', col_first, col_first);



    -- change the temp table name to the name given as parameter, if not blank

    if length(target_table) > 0 then

        execute format('alter table temp_table rename to %I', target_table);

    end if;



end;



$BODY$

  LANGUAGE plpgsql VOLATILE

  COST 100;

ALTER FUNCTION load_csv_file(text, text, integer)

  OWNER TO postgres;

Note: There is a common issue with importing text files related to encoding. The csv file should be in UTF-8 format. However, sometimes this is not quite achieved by the programs, which try to do the encoding. I have overcome this issue by opening the file in Notepad++ and converting it to ANSI and back to UTF8.