Port sql_fn from Perl to Julia

This is a convenience function that I
started using in Perl in 2022.
I wish I was using this style in 1998.
It removes noise from DB code.

src/db.jl

@@ -2,6 +2,24 @@ using SQLite
 using DataFrames
 using Dates
 
+"""
+    sql_fn(db)
+
+Return a function that takes an SQL and optional bind parameters
+and runs the query and returns the results as a DataFrame.
+
+```julia
+db = SQLite.DB("sql/wn.db")
+sql = WeatherNews.DB.sql_fn(db)
+res = sql("SELECT * FROM cancellation")
+```
+"""
+function sql_fn(db)
+    function sql(query, params=[])
+        DBInterface.execute(db, query, params) |> DataFrame
+    end
+end
+
 """
 Find or create a caster by short name `n`.
 """