More useful notes

go-sql-database/try-sqlite/main.go

@@ -94,6 +94,8 @@ func main() {
 	// If never want to do string concat from user input into a sql statement you run unless you like sql injection attacks
 	// expects to return one row. If no row it will delay throwing error until Scan is called
 	row := db.QueryRow("SELECT id, subject, todo FROM todos WHERE id = ?", 1)
+	// Scan does the heavily lifting for you when casting from db type to go type. It will cast based on the variable type.
+	// failures of course will be returned as part of the err
 	err = row.Scan(&id, &subject, &todo)
 	if err != nil {
 		log.Fatal(err)
@@ -102,13 +104,26 @@ func main() {
 	log.Printf("id: %d, subject: %s, todo: %s", id, subject, todo)
 
 	// This should error on scan
-
-	row = db.QueryRow("SELECT * FROM todos WHERE id = ?", 100_000)
-	err = row.Scan(&id, &subject, &todo)
+	// We can also use this short hand!
+	err = db.QueryRow("SELECT * FROM todos WHERE id = ?", 100_000).Scan(&id, &subject, &todo)
 	if err != nil {
 		log.Print(err.Error())
 	}
 
 	// There is no row.Close(). Rows objects have a Close() method. No explicit closing required.
 
+	//Prepared Queries
+	// If you will be using the same query over and over you should just prepare the query.
+	// $N is the postgres query param which SQLite can use too ? is mysql's
+
+	//Under the hood, db.Query() actually prepares, executes, and closes a prepared statement
+	// That’s three round-trips to the database.
+	stmt, err := db.Prepare("SELECT * FROM todos WHERE id = $N")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	//This prepared statement *sql.Stmt is tied to the database connection from which it was created, and it holds onto that connection until you call stmt.Close()
+	defer stmt.Close()
+
 }