Fix bugs: Logically Fail to Login in when table is empty

userAuth.cpp

@@ -1,5 +1,6 @@
 #include "userAuth.h"
 #include "tools.h"
+#include <cstdlib>
 
 const char *CREATE_USER_TABLE = "CREATE TABLE IF NOT EXISTS user_data ("
                                 "id INTEGER PRIMARY KEY AUTOINCREMENT,"
@@ -33,6 +34,32 @@ void init_user_data(sqlite3 *db) {
   };
 };
 
+bool is_user_table_empty(sqlite3 *db) {
+  const char *query = "SELECT COUNT(*) FROM user_data;";
+  sqlite3_stmt *stmt;
+  bool isEmpty = true;
+
+  // 准备SQL语句
+  if (sqlite3_prepare_v2(db, query, -1, &stmt, nullptr) != SQLITE_OK) {
+    std::cerr << "Failed to prepare statement: " << sqlite3_errmsg(db)
+              << std::endl;
+    return true; // 假设出错时表为空（根据你的需求可能需要调整）
+  }
+
+  // 执行查询
+  if (sqlite3_step(stmt) == SQLITE_ROW) {
+    int count = sqlite3_column_int(stmt, 0);
+    isEmpty = (count == 0);
+  } else {
+    std::cerr << "Failed to execute query: " << sqlite3_errmsg(db) << std::endl;
+  }
+
+  // 释放语句
+  sqlite3_finalize(stmt);
+
+  return isEmpty;
+}
+
 void register_user(sqlite3 *db, const string &username,
                    const string &userpassword) {
   sqlite3_stmt *stmt;