diff --git a/2.3.cpp b/2.3.cpp
new file mode 100644
index 0000000..b4733e7
--- /dev/null
+++ b/2.3.cpp
@@ -0,0 +1,92 @@
+#include "MySQLWrapper.h"
+#include <iostream>
+#include <vector>
+#include <map>
+#include <set>
+#include <cstdlib>
+#include <cstdio>
+#include <cstring>
+#include <algorithm>
+#include <fstream>
+using namespace std;
+
+#include "local_db_account.h"
+#include "util.hpp"
+
+int main()
+{
+    MySQLConn conn;
+    conn.connect("127.0.0.1",db_user,db_passwd,"bigdata3",3306);
+    cout<<"Connected to DB"<<endl;
+    conn.exec("set names gbk",nullptr);
+
+    map<string,vector<int>> mp;
+    conn.exec("select job_city,count(*) from lagou_job group by job_city",[&](MySQLResult& res)
+              {
+                  res.stepRow([&](char** val,unsigned long* len)
+                              {
+                                  string city(val[0]);
+                                  int cc=ParseInt(val[1]);
+                                  mp[Trim(city)].push_back(cc);
+                              });
+              });
+
+    conn.exec("use bigdata5",nullptr);
+    conn.exec("select job_city,count(*) from pages group by job_city",[&](MySQLResult& res)
+              {
+                  res.stepRow([&](char** val,unsigned long* len)
+                              {
+                                  string city(val[0]);
+                                  int cc=ParseInt(val[1]);
+                                  mp[Trim(city)].push_back(cc);
+                              });
+              });
+
+    ofstream ofs("result/2.3.csv");
+
+    for(auto iter=mp.begin();iter!=mp.end(); )
+    {
+        bool updated=false;
+        for(auto xiter=mp.begin();xiter!=iter; )
+        {
+            if(iter->first.find(xiter->first)!=string::npos)
+            {
+                /// Found something?
+                /// targetvec.push_back(thisvec) : Add current vector to the previous vector.
+                xiter->second.insert(xiter->second.end(),
+                                       iter->second.begin(),iter->second.end());
+
+
+                /// iter should now be deleted. Get next iter first
+                auto nowiter=iter;
+                ++iter;
+                mp.erase(nowiter);
+
+                /// Stop internal loop.
+                updated=true;
+                break;
+            }
+            else ++xiter;
+        }
+
+        if(!updated) ++iter;
+    }
+
+    #define cout ofs
+
+    for(auto& pr:mp)
+    {
+        cout<<pr.first<<",";
+        int sum=0;
+        int n=pr.second.size();
+        for(int i=0;i<n;i++)
+        {
+            sum+=pr.second[i];
+        }
+        cout<<sum<<endl;
+    }
+
+    #undef cout
+
+    return 0;
+}