diff --git a/src/main/java/de/srsoftware/widerhall/data/Database.java b/src/main/java/de/srsoftware/widerhall/data/Database.java
index 66e1d27..5bc4251 100644
--- a/src/main/java/de/srsoftware/widerhall/data/Database.java
+++ b/src/main/java/de/srsoftware/widerhall/data/Database.java
@@ -4,7 +4,6 @@ import de.srsoftware.widerhall.Configuration;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.File;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.ResultSet;
@@ -12,17 +11,16 @@ import java.sql.SQLException;
 import java.util.*;
 
 import static de.srsoftware.widerhall.Util.t;
+import static de.srsoftware.widerhall.Constants.*;
 
 public class Database {
-    public static final String EMAIL = "email";
-    public static final String NAME = "name";
     public static final String HASHED_PASS = "hashedPassword";
     public static final String SALT = "salt";
 
     private static final Logger LOG = LoggerFactory.getLogger(Database.class);
     private static final String VARCHAR = "VARCHAR(255)";
     private static Database singleton = null;
-    private static Connection conn;
+    private final Connection conn;
 
     public Request insertInto(String tbName) {
         return query("INSERT INTO "+tbName);
@@ -31,8 +29,8 @@ public class Database {
     public class Request{
 
         private final String sql;
-        private HashMap<String,List<Object>> where = new HashMap<>();
-        private HashMap<String,Object> values = new HashMap<>();
+        private final HashMap<String,List<Object>> where = new HashMap<>();
+        private final HashMap<String,Object> values = new HashMap<>();
 
         public Request(String sql) {
             this.sql = sql;
@@ -45,7 +43,7 @@ public class Database {
 
         public Request where(String key, Object value) {
             var list = where.get(key);
-            if (list == null) where.put(key,list = new ArrayList<Object>());
+            if (list == null) where.put(key,list = new ArrayList<>());
             list.add(value);
             return this;
         }
@@ -62,15 +60,17 @@ public class Database {
 
         public void run() throws SQLException {
             var sb = new StringBuilder(sql);
-            var args = new ArrayList<Object>();
+            var args = new ArrayList<>();
             if (!values.isEmpty()){
                 var keys = new ArrayList<String>();
                 for (var entry : values.entrySet()) {
                     keys.add(entry.getKey());
                     args.add(entry.getValue());
                 }
-                sb.append("("+String.join(", ",keys)+")");
-                sb.append(" VALUES ");
+                sb.append("(")
+                        .append(String.join(", ",keys))
+                        .append(")")
+                        .append(" VALUES ");
                 var arr = new String[args.size()];
                 Arrays.fill(arr,"?");
                 var marks = String.join(", ",arr);
@@ -91,7 +91,7 @@ public class Database {
 
         public ResultSet exec() throws SQLException {
             var sb = new StringBuilder(sql);
-            var args = new ArrayList<Object>();
+            var args = new ArrayList<>();
             if (!where.isEmpty()){
                 var clauses = new ArrayList<String>();
                 sb.append(" WHERE ");
@@ -109,7 +109,7 @@ public class Database {
             var sql = sb.toString();
             LOG.debug(sql);
             try {
-                var stmt = conn.prepareStatement(sql);
+                var stmt = Database.this.conn.prepareStatement(sql);
                 if (!args.isEmpty()) {
                     for (int i = 0; i < args.size(); i++) stmt.setObject(i+1, args.get(i));
                 }