fix: use isset() when checking table property value (#52)

We can't access the `$this->table` property before initialization, so let's use `isset()` to check if the property has a value.

Reviewed-on: https://codeberg.org/vlw/php-mysql/pulls/52

src/MySQL.php

@@ -35,7 +35,7 @@
 		*/
 
 		private function throw_if_no_table() {
-			if (!$this->table) {
+			if (!isset($this->table)) {
 				throw new Exception("No table name defined");
 			}
 		}
@@ -163,17 +163,8 @@
 				return $this;
 			}
 
-			// Set LIMIT without range directly as integer
-			if (is_int($limit)) {
-				$this->limit = $limit;
-				return $this;
-			}
-
-			// No offset defined, set limit property directly as string
-			if (is_null($offset)) {
-				$this->limit = (string) $limit;
-				return $this;
-			}
+			// Coerce offset to zero if no offset is defined
+			$offset = $offset ?? 0;
 
 			// Set limit and offset as SQL CSV
 			$this->limit = "{$offset},{$limit}";
@@ -277,9 +268,14 @@
 			$this->throw_if_no_table();
 
 			// Set DELETE WHERE conditions from arguments
-			$this->where(...$conditions);
+			if ($conditions) {
+				$this->where(...$conditions);
+			}
 
-			$sql = "DELETE FROM `{$this->table}` WHERE {$this->filter_sql}";
+			// Get array of SQL WHERE string and filter values
+			$filter_sql = !is_null($this->filter_sql) ? " WHERE {$this->filter_sql}" : "";
+
+			$sql = "DELETE FROM `{$this->table}`{$filter_sql}";
 			return $this->execute_query($sql, self::to_list_array($this->filter_values));
 		}