更新代码，适配php7.4

thinkphp/library/think/Response.php

@@ -395,7 +395,7 @@ class Response
         if (null == $this->content) {
             $content = $this->output($this->data);
 
-            if (null !== $content && !is_string($content) && !is_numeric($content) && !is_callable([
+            if (null !== $content && !is_string($content) && !is_numeric($content) && !is_bool($content) && !is_array($content) && !is_callable([
                 $content,
                 '__toString',
             ])
@@ -403,7 +403,13 @@ class Response
                 throw new \InvalidArgumentException(sprintf('variable type error： %s', gettype($content)));
             }
 
-            $this->content = (string) $content;
+            if (is_bool($content)) {
+                $this->content = $content ? 'true' : 'false';
+            } elseif (is_array($content)) {
+                $this->content = json_encode($content);
+            } else {
+                $this->content = (string) $content;
+            }
         }
 
         return $this->content;

thinkphp/library/think/db/Connection.php

@@ -1813,11 +1813,10 @@ abstract class Connection
      * @access public
      * @return integer
      */
-    public function getExecuteTimes()
+    public function getExecuteTimes() 
     {
-        return Db::$executeTimes;
+        return json(['times' => Db::$executeTimes]);
     }
-
     /**
      * 关闭数据库（或者重新连接）
      * @access public

thinkphp/library/think/db/Query.php

@@ -565,7 +565,7 @@ class Query
                         $seq = (ord(substr($type($value), 0, 1)) % $rule['num']) + 1;
                     } else {
                         // 按照字段的首字母的值分表
-                        $seq = (ord($value{0}) % $rule['num']) + 1;
+                        $seq = (ord($value[0]) % $rule['num']) + 1;
                     }
             }
             return $this->getTable() . '_' . $seq;