storage/sql: add a SQL storage implementation

This change adds support for SQLite3, and Postgres.

storage/sql/crud_test.go

@@ -0,0 +1,55 @@
+package sql
+
+import (
+	"database/sql"
+	"reflect"
+	"testing"
+)
+
+func TestDecoder(t *testing.T) {
+	db, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	if _, err := db.Exec(`create table foo ( id integer primary key, bar blob );`); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := db.Exec(`insert into foo ( id, bar ) values (1, ?);`, []byte(`["a", "b"]`)); err != nil {
+		t.Fatal(err)
+	}
+	var got []string
+	if err := db.QueryRow(`select bar from foo where id = 1;`).Scan(decoder(&got)); err != nil {
+		t.Fatal(err)
+	}
+	want := []string{"a", "b"}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("wanted %q got %q", want, got)
+	}
+}
+
+func TestEncoder(t *testing.T) {
+	db, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	if _, err := db.Exec(`create table foo ( id integer primary key, bar blob );`); err != nil {
+		t.Fatal(err)
+	}
+	put := []string{"a", "b"}
+	if _, err := db.Exec(`insert into foo ( id, bar ) values (1, ?)`, encoder(put)); err != nil {
+		t.Fatal(err)
+	}
+
+	var got []byte
+	if err := db.QueryRow(`select bar from foo where id = 1;`).Scan(&got); err != nil {
+		t.Fatal(err)
+	}
+	want := []byte(`["a","b"]`)
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("wanted %q got %q", want, got)
+	}
+}