Can I automatically create a table in PostgreSQL from a csv file with headers?

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$BODY$declareiter integer; -- dummy integer to iterate columns withcol text; -- variable to keep the column name at each iterationcol_first text; -- first column name, e.g., top left corner on a csv file or spreadsheetbegin    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.

I am using csvsql to generate the table layout (it will automatically guess the format):

head -n 20 table.csv | csvsql --no-constraints --tables table_name 

And then I use \COPY in psql. That's for me the fastest way to import CSV file.

You can also use sed with csvsql in order to get the desired datatype:

head -n 20 table.csv | csvsql --no-constraints --tables table_name  | sed 's/DECIMAL/NUMERIC/' | sed 's/VARCHAR/TEXT/'