Create hash with keys are table names, values are column names - ruby

Question

I would like to iterate an array that has a database table names, I would like to create a hash like this:
{"table1"=>[column1,...,columnN],"table2"=>[column1,...,columnM]...}
This is what I did so far:
arr_table_names = ['table1','table2','table3']
arr_table_names.each do |table|
rs = pg_conn.exec 'SELECT * FROM table WHERE Id=0'
column_names = rs.nfields
h = Hash.new{|hsh,key| hsh[key] = [] }
h[table].push ??? column_names ?? I don't know how in this line
end
I tried to use Sebastian's solution, but got a syntax error:
def check_tables_same_content(table1,table2)
result = %w[#{table1} #{table2}].each_with_object([]) do |table, arr|
arr << { table.to_sym => #pg_conn.exec("SELECT * FROM #{table} WHERE false").fields }
end
puts result2
end
check_tables_same_content('company','company2')
company.rb:21:in `exec': ERROR: syntax error at or near "#" (PG::SyntaxError)
LINE 1: SELECT * FROM #{table1} WHERE false
^
Note that I am not looking on how to return column names.

Answer 1

Use .map to create a new array and pass the block. This should work:
arr_table_names.map do |table|
rs = pg_conn.execute "SELECT * FROM #{table} WHERE Id=0"
{table => rs.fields}
end
Update, you wanted a hash with the table names as keys, and columns as values so:
arr_table_names = ['table1','table2','table3']
hash = {}
arr_table_names.each do |table|
rs = pg_conn.execute "SELECT * FROM #{table} WHERE Id=0"
hash[table] = rs.fields
end
Update 2, you want the row data as an array for each column(key) in the hash:
arr_table_names = ['table1','table2','table3']
hash = {}
arr_table_names.each do |table|
rows = pg_conn.execute "SELECT * FROM #{table}"
hash[table] = rows.entries.map(&:values)
end