diff --git a/docs/how_to_dev_miniob_by_vscode.md b/docs/how_to_dev_miniob_by_vscode.md
index 29d7de413c982e2f399a229cdc6f4c2755c599ea..014754b2f49bd97ab769e80401f7f2e87b01c2da 100644
--- a/docs/how_to_dev_miniob_by_vscode.md
+++ b/docs/how_to_dev_miniob_by_vscode.md
@@ -24,11 +24,10 @@ UBUNTU_CODENAME=focal
 2. cmake
 3. make
 4. gcc/g++
-
-3. libevent
-5. googletest
-6. jsoncpp
-7. git
+5. libevent
+6. googletest
+7. jsoncpp
+8. git
 
 ## 获取代码
 ```bash
diff --git a/src/observer/net/server.cpp b/src/observer/net/server.cpp
index 47e2e529874eecec048cfb0b3693c759ec43b5ef..e6c887f1d40ed745f07e368e743d2f614b7ba03e 100644
--- a/src/observer/net/server.cpp
+++ b/src/observer/net/server.cpp
@@ -189,7 +189,6 @@ int Server::send(ConnectionContext *client, const char *buf, int data_len)
   TimerStat writeStat(*write_socket_metric_);
 
   MUTEX_LOCK(&client->mutex);
-  int wlen = 0;
   int ret = common::writen(client->fd, buf, data_len);
   if (ret < 0) {
     LOG_ERROR("Failed to send data back to client. ret=%d, error=%s", ret, strerror(errno));
diff --git a/src/observer/sql/stmt/select_stmt.cpp b/src/observer/sql/stmt/select_stmt.cpp
index 580c857a4141015939c534de0d1d5a473483b966..9d433c8cdf731dd7c649dd677951b371e297829c 100644
--- a/src/observer/sql/stmt/select_stmt.cpp
+++ b/src/observer/sql/stmt/select_stmt.cpp
@@ -46,7 +46,7 @@ RC SelectStmt::create(Db *db, const Selects &select_sql, Stmt *&stmt)
   // collect tables in `from` statement
   std::vector<Table *> tables;
   std::unordered_map<std::string, Table *> table_map;
-  for (int i = 0; i < select_sql.relation_num; i++) {
+  for (size_t i = 0; i < select_sql.relation_num; i++) {
     const char *table_name = select_sql.relations[i];
     if (nullptr == table_name) {
       LOG_WARN("invalid argument. relation name is null. index=%d", i);