feat: remove table model by passing null to with() (#19)

* feat: remove table model by passing null to with()

* feat(doc): add with() in README

README.md

@@ -40,7 +40,7 @@ Statement|Method
 `ORDER BY`|[`order()`](#order-by)
 `LIMIT`|[`limit()`](#limit)
 
----
+----
 
 `Example table name: beverages`
 id|beverage_type|beverage_name|beverage_size
@@ -282,3 +282,13 @@ $coffee = $db->for("beverages")->limit([3 => 2])->select(["beverage_name", "beve
   // ...etc
 ]
 ```
+
+----
+
+# Restrict affected/returned database columns to table model
+
+Chain and pass an array to `MySQL->with()` before a `select()`, `update()`, or `insert()` method to limit which columns will be returned/affected. It will use the **values** of the array so it can be either sequential or associative.
+
+**This method will cause `select()`, `update()`, and `insert()` to ignore any columns that are not present in the passed table model.**
+
+You can remove an already set table model by passing `null` to `MySQL->with()`

src/MySQL.php

@@ -48,7 +48,13 @@
 		}
 
 		// Restrict query to array of column names
-		public function with(array $model): self {
+		public function with(?array $model = null): self {
+			// Remove table model if empty
+			if (!$model) {
+				$this->model = null;
+				return $this;
+			}
+
 			// Reset table model
 			$this->model = [];