ODBC example for prepared statement doesn't work

General Usage
2

I should note, that inserting the values directly works OK, so it’s not the table definition or the values. It looks like the prepared statement doesn’t work as documented.

julia> for row in eachrow(df)
           println(row)
           col1 = row[:col1]
           col2 = row[:col2]
           col3 = row[:col3]
           ODBC.execute!(dsn, "INSERT INTO cool_table (col1, col2, col3) VALUES ($col1, $col2, '$col3')")
       end

DataFrameRow (row 1)
col1  1
col2  4.0
col3  hey

DataFrameRow (row 2)
col1  2
col2  5.0
col3  there

DataFrameRow (row 3)
col1  3
col2  6.0
col3  sailor

SQL> select * from cool_table;
  COL1   COL2 COL3     
     1      4 hey      
     2      5 there    
     3      6 sailor