diff --git a/amex-2022-10-20/0_setup/main.go b/amex-2022-10-20/0_setup/main.go
index 2953b4e..df48234 100644
--- a/amex-2022-10-20/0_setup/main.go
+++ b/amex-2022-10-20/0_setup/main.go
@@ -15,14 +15,18 @@ func main() {
 	q := flag.String("q", "show tables", "query to execute")
 	flag.Parse()
 
+	query := strings.Trim(strings.TrimSpace(*q), ";")
+	if len(query) == 0 {
+		panic("refusing empty query")
+	}
+	query += ";"
+	log.Printf("%s", query)
+
 	db, err := sql.Open("sqlite3", *dbpath)
 	if err != nil {
 		panic(err)
 	}
 
-	query := strings.Trim(strings.TrimSpace(*q), ";") + ";"
-	log.Printf("%s", query)
-
 	if strings.HasPrefix(strings.ToUpper(strings.TrimSpace(query)), "SELECT") {
 		rows, err := db.Query(query)
 		if err != nil {
diff --git a/amex-2022-10-20/3_/db.db b/amex-2022-10-20/3_/db.db
new file mode 100644
index 0000000..e52c3d0
Binary files /dev/null and b/amex-2022-10-20/3_/db.db differ
diff --git a/amex-2022-10-20/3_/go.mod b/amex-2022-10-20/3_/go.mod
deleted file mode 100644
index f39e3a7..0000000
--- a/amex-2022-10-20/3_/go.mod
+++ /dev/null
@@ -1,3 +0,0 @@
-module 3_
-
-go 1.18
diff --git a/amex-2022-10-20/3_/mvp.sh b/amex-2022-10-20/3_/mvp.sh
new file mode 100644
index 0000000..71c7512
--- /dev/null
+++ b/amex-2022-10-20/3_/mvp.sh
@@ -0,0 +1,31 @@
+#! /bin/bash
+
+main() {
+   set -e
+   set -o pipefail
+
+   local bin=../0_setup/0_setup
+   local cmds=(
+      'DROP TABLE IF EXISTS events'
+      '
+         CREATE TABLE events (
+            sensor_id integer not null,
+            event_type integer not null
+         );
+      '
+      'INSERT INTO events VALUES (2, 2)'
+      'INSERT INTO events VALUES (2, 4)'
+      'INSERT INTO events VALUES (2, 2)'
+      'INSERT INTO events VALUES (3, 2)'
+      'INSERT INTO events VALUES (2, 3)'
+      "$@"
+   )
+
+   for cmd in "${cmds[@]}"; do
+      echo =================
+      $bin -q "$cmd"
+      echo
+   done
+}
+
+main "$@"