diff --git a/sql/engines/mongo.py b/sql/engines/mongo.py
index 8686dd4470..fb01995d5b 100644
--- a/sql/engines/mongo.py
+++ b/sql/engines/mongo.py
@@ -292,9 +292,8 @@ def exec_cmd(self, sql, db_name=None, slave_ok=""):
             sql_len = len(sql)
             is_load = False  # 默认不使用load方法执行mongodb sql语句
             try:
-                if (
-                    not sql.startswith("var host=") and sql_len > 4000
-                ):  # 在master节点执行的情况，如果sql长度大于4000,就采取load js的方法
+                if not sql.startswith("var host=") and sql_len > 4000:
+                  # 在master节点执行的情况，如果sql长度大于4000,就采取load js的方法
                     # 因为用mongo load方法执行js脚本，所以需要重新改写一下sql，以便回显js执行结果
                     sql = "var result = " + sql + "\nprintjson(result);"
                     # 因为要知道具体的临时文件位置，所以用了NamedTemporaryFile模块
@@ -303,77 +302,12 @@ def exec_cmd(self, sql, db_name=None, slave_ok=""):
                     )
                     fp.write(sql.encode("utf-8"))
                     fp.seek(0)  # 把文件指针指向开始，这样写的sql内容才能落到磁盘文件上
-                    if self.user and self.password:
-                        cmd = "{mongo} --quiet -u {uname} -p '{password}' {host}:{port}/{auth_db} <<\\EOF\ndb=db.getSiblingDB(\"{db_name}\");{slave_ok}load('{tempfile_}')\nEOF".format(
-                        mongo=mongo,
-                        uname=self.user,
-                        password=self.password,
-                        host=self.host,
-                        port=self.port,
-                        db_name=db_name,
-                        sql=sql,
-                        auth_db=auth_db,
-                        slave_ok=slave_ok,
-                        tempfile_=fp.name,
-                    )
-                    else:
-                        cmd = "{mongo} --quiet  {host}:{port}/{auth_db} <<\\EOF\ndb=db.getSiblingDB(\"{db_name}\");{slave_ok}load('{tempfile_}')\nEOF".format(
-                        mongo=mongo,
-                        host=self.host,
-                        port=self.port,
-                        db_name=db_name,
-                        sql=sql,
-                        auth_db=auth_db,
-                        slave_ok=slave_ok,
-                        tempfile_=fp.name,
-                    )        
+                    cmd = self._build_cmd(db_name, auth_db, slave_ok, fp.name, is_load=True)
                     is_load = True  # 标记使用了load方法，用来在finally里面判断是否需要强制删除临时文件
-                elif (
-                    not sql.startswith("var host=") and sql_len < 4000
-                ):  # 在master节点执行的情况， 如果sql长度小于4000,就直接用mongo shell执行，减少磁盘交换，节省性能
-                    if self.user and self.password:
-                        cmd = "{mongo} --quiet -u {uname} -p '{password}' {host}:{port}/{auth_db} <<\\EOF\ndb=db.getSiblingDB(\"{db_name}\");{slave_ok}printjson({sql})\nEOF".format(
-                        mongo=mongo,
-                        uname=self.user,
-                        password=self.password,
-                        host=self.host,
-                        port=self.port,
-                        db_name=db_name,
-                        sql=sql,
-                        auth_db=auth_db,
-                        slave_ok=slave_ok,
-                    )
-                    else:
-                        cmd = "{mongo} --quiet  {host}:{port}/{auth_db} <<\\EOF\ndb=db.getSiblingDB(\"{db_name}\");{slave_ok}printjson({sql})\nEOF".format(
-                        mongo=mongo,
-                        host=self.host,
-                        port=self.port,
-                        db_name=db_name,
-                        sql=sql,
-                        auth_db=auth_db,
-                        slave_ok=slave_ok,
-                    )
+                elif not sql.startswith("var host=") and sql_len < 4000:  # 在master节点执行的情况， 如果sql长度小于4000,就直接用mongo shell执行，减少磁盘交换，节省性能
+                    cmd = self._build_cmd(db_name, auth_db, slave_ok, sql=sql)
                 else:
-                    if self.user and self.password:
-                        cmd = "{mongo} --quiet -u {user} -p '{password}' {host}:{port}/{auth_db} <<\\EOF\nrs.slaveOk();{sql}\nEOF".format(
-                        mongo=mongo,
-                        user=self.user,
-                        password=self.password,
-                        host=self.host,
-                        port=self.port,
-                        db_name=db_name,
-                        sql=sql,
-                        auth_db=auth_db,
-                    )
-                    else:
-                        cmd = "{mongo} --quiet {host}:{port}/{auth_db} <<\\EOF\nrs.slaveOk();{sql}\nEOF".format(
-                        mongo=mongo,
-                        host=self.host,
-                        port=self.port,
-                        db_name=db_name,
-                        sql=sql,
-                        auth_db=auth_db,
-                    )
+                    cmd = self._build_cmd(db_name, auth_db, sql=sql, slave_ok="rs.slaveOk();")
                 p = subprocess.Popen(
                     cmd,
                     shell=True,
@@ -403,7 +337,68 @@ def exec_cmd(self, sql, db_name=None, slave_ok=""):
                 if is_load:
                     fp.close()
         return msg
-
+    # 用来进行判断是否有用户名与密码情况，进而返回要执行的mongo命令
+    def _build_cmd(self, db_name, auth_db, slave_ok="", tempfile_=None, sql=None, is_load=False):
+        """构建命令行"""
+        if is_load:
+            if self.user and self.password:
+                return (
+                    "{mongo} --quiet -u {uname} -p '{password}' {host}:{port}/{auth_db} <<\\EOF\n"
+                    "db=db.getSiblingDB(\"{db_name}\");{slave_ok}load('{tempfile_}')\nEOF"
+                ).format(
+                    mongo=mongo,
+                    uname=self.user,
+                    password=self.password,
+                    host=self.host,
+                    port=self.port,
+                    db_name=db_name,
+                    auth_db=auth_db,
+                    slave_ok=slave_ok,
+                    tempfile_=tempfile_,
+                )
+            else:
+                return (
+                    "{mongo} --quiet {host}:{port}/{auth_db} <<\\EOF\n"
+                    "db=db.getSiblingDB(\"{db_name}\");{slave_ok}load('{tempfile_}')\nEOF"
+                ).format(
+                    mongo=mongo,
+                    host=self.host,
+                    port=self.port,
+                    db_name=db_name,
+                    auth_db=auth_db,
+                    slave_ok=slave_ok,
+                    tempfile_=tempfile_,
+                )
+        else:
+            if self.user and self.password:
+                return (
+                    "{mongo} --quiet -u {uname} -p '{password}' {host}:{port}/{auth_db} <<\\EOF\n"
+                    "db=db.getSiblingDB(\"{db_name}\");{slave_ok}printjson({sql})\nEOF"
+                ).format(
+                    mongo=mongo,
+                    uname=self.user,
+                    password=self.password,
+                    host=self.host,
+                    port=self.port,
+                    db_name=db_name,
+                    auth_db=auth_db,
+                    slave_ok=slave_ok,
+                    sql=sql,
+                )
+            else:
+                return (
+                    "{mongo} --quiet {host}:{port}/{auth_db} <<\\EOF\n"
+                    "db=db.getSiblingDB(\"{db_name}\");{slave_ok}printjson({sql})\nEOF"
+                ).format(
+                    mongo=mongo,
+                    host=self.host,
+                    port=self.port,
+                    db_name=db_name,
+                    auth_db=auth_db,
+                    slave_ok=slave_ok,
+                    sql=sql,
+                )
+        
     def get_master(self):
         """获得主节点的port和host"""