diff --git a/core/Api/CreateApiKey.class.php b/core/Api/CreateApiKey.class.php
index a0c3c3c..d240b0d 100644
--- a/core/Api/CreateApiKey.class.php
+++ b/core/Api/CreateApiKey.class.php
@@ -22,6 +22,7 @@ class CreateApiKey extends Request {
 
     $this->success = $sql->insert("ApiKey", array("user_id", "api_key", "valid_until"))
       ->addRow($this->user->getId(), $apiKey, $validUntil)
+      ->returning("uid")
       ->execute();
 
     $this->lastError = $sql->getLastError();
diff --git a/core/Configuration/CreateDatabase.class.php b/core/Configuration/CreateDatabase.class.php
index 8d18a6a..6cba3d4 100644
--- a/core/Configuration/CreateDatabase.class.php
+++ b/core/Configuration/CreateDatabase.class.php
@@ -25,8 +25,7 @@ class CreateDatabase {
 
     $queries[] = $sql->insert("Language", array("uid", "code", "name"))
       ->addRow(1, "en_US", 'American English')
-      ->addRow(2, "de_DE", 'Deutsch Standard')
-      ->onDuplicateKeyStrategy(new UpdateStrategy(array("name" => new Column("name"))));
+      ->addRow(2, "de_DE", 'Deutsch Standard');
 
     $queries[] = $sql->createTable("User")
       ->addSerial("uid")
@@ -56,7 +55,7 @@ class CreateDatabase {
     $queries[] = $sql->createTable("UserToken")
       ->addInt("user_id")
       ->addString("token", 36)
-      ->addEnum("type", array("password_reset", "confirmation"))
+      ->addEnum("token_type", array("password_reset", "confirmation"))
       ->addDateTime("valid_until")
       ->foreignKey("user_id", "User", "uid", new CascadeStrategy());
 
@@ -68,8 +67,7 @@ class CreateDatabase {
 
     $queries[] = $sql->insert("Group", array("uid", "name"))
       ->addRow(1, "Default")
-      ->addRow(2, "Administrator")
-      ->onDuplicateKeyStrategy(new UpdateStrategy(array("name" => new Column("name"))));
+      ->addRow(2, "Administrator");
 
     $queries[] = $sql->createTable("UserGroup")
       ->addInt("user_id")
diff --git a/core/Documents/Install.class.php b/core/Documents/Install.class.php
index c0b429f..3f0edc8 100644
--- a/core/Documents/Install.class.php
+++ b/core/Documents/Install.class.php
@@ -139,12 +139,6 @@ namespace Documents\Install {
           $success = false;
       }
 
-      if(!function_exists('mysqli_connect')) {
-        $link = $this->createExternalLink("https://secure.php.net/manual/en/mysqli.setup.php");
-        $failedRequirements[] = "mysqli is not enabled yet. See: $link";
-        $success = false;
-      }
-
       if(!$success) {
         $msg = "The following requirements failed the check:<br>" .
           $this->createUnorderedList($failedRequirements);
@@ -196,7 +190,7 @@ namespace Documents\Install {
         $missingInputs[] = "Type";
       }
 
-      $supportedTypes = array("mysql"); # , "oracle", "postgres");
+      $supportedTypes = array("mysql", "postgres"); # , "oracle", "postgres");
       if(!$success) {
         $msg = "Please fill out the following inputs:<br>" .
           $this->createUnorderedList($missingInputs);
@@ -216,14 +210,21 @@ namespace Documents\Install {
         if(!($sql instanceof \Driver\SQL\SQL)) {
           $msg = "Error connecting to database: " . str($sql);
         } else if(!$sql->isConnected()) {
-          $msg = "Error connecting to database:<br>" . $sql->getLastError();
+          if (!$sql->checkRequirements()) {
+            $driverName = $sql->getDriverName();
+            $installLink = "https://www.php.net/manual/en/$driverName.setup.php";
+            $link = $this->createExternalLink($installLink);
+            $msg = "$driverName is not enabled yet. See: $link";
+          } else {
+            $msg = "Error connecting to database:<br>" . $sql->getLastError();
+          }
         } else {
 
           $msg = "";
           $success = true;
           $queries = \Configuration\CreateDatabase::createQueries($sql);
           foreach($queries as $query) {
-            if (!$query->execute()) {
+            if (!($res = $query->execute())) {
               $msg = "Error creating tables: " . $sql->getLastError();
               $success = false;
               break;
diff --git a/core/Driver/SQL/MySQL.class.php b/core/Driver/SQL/MySQL.class.php
index 55f675c..2e2e5f2 100644
--- a/core/Driver/SQL/MySQL.class.php
+++ b/core/Driver/SQL/MySQL.class.php
@@ -25,7 +25,16 @@ use \Driver\SQL\Constraint\ForeignKey;
 class MySQL extends SQL {
 
   public function __construct($connectionData) {
-     parent::__construct("mysql", $connectionData);
+     parent::__construct($connectionData);
+     $this->installLink = ;
+  }
+
+  public function checkRequirements() {
+    return function_exists('mysqli_connect');
+  }
+
+  public abstract function getDriverName() {
+    return 'mysqli';
   }
 
   public function connect() {
@@ -48,7 +57,7 @@ class MySQL extends SQL {
       return false;
     }
 
-    mysqli_set_charset($this->connection, $this->connectionData->getProperty('encoding'));
+    mysqli_set_charset($this->connection, $this->connectionData->getProperty('encoding', 'UTF-8'));
     return true;
   }
 
@@ -58,7 +67,6 @@ class MySQL extends SQL {
     }
 
     mysqli_close($this->connection);
-    $this->connection = NULL;
   }
 
   public function getLastError() {
@@ -216,8 +224,7 @@ class MySQL extends SQL {
             $columnName = $value->getName();
             $updateValues[] = "`$key`=`$columnName`";
           } else {
-            $updateValues[] = "`$key`=?";
-            $parameters[] = $value;
+            $updateValues[] = "`$key`=" . $this->addValue($value, $parameters);
           }
         }
 
@@ -319,33 +326,6 @@ class MySQL extends SQL {
     return $this->execute($query, $params);
   }
 
-  protected function buildCondition($condition, &$params) {
-    if ($condition instanceof \Driver\SQL\Condition\CondOr) {
-      $conditions = array();
-      foreach($condition->getConditions() as $cond) {
-        $conditions[] = $this->buildCondition($cond, $params);
-      }
-      return "(" . implode(" OR ", $conditions) . ")";
-    } else if ($condition instanceof \Driver\SQL\Condition\Compare) {
-      $column = $condition->getColumn();
-      $value = $condition->getValue();
-      $operator = $condition->getOperator();
-      return $column . $operator . $this->addValue($value, $params);
-    } else if ($condition instanceof \Driver\SQL\Condition\CondBool) {
-      return $condition->getValue();
-    } else if (is_array($condition)) {
-      if (count($condition) == 1) {
-        return $this->buildCondition($condition[0], $params);
-      } else {
-        $conditions = array();
-        foreach($condition as $cond) {
-          $conditions[] = $this->buildCondition($cond, $params);
-        }
-        return implode(" AND ", $conditions);
-      }
-    }
-  }
-
   public function getColumnDefinition($column) {
     $columnName = $column->getName();
 
@@ -380,7 +360,11 @@ class MySQL extends SQL {
     }
 
     $notNull = $column->notNull() ? " NOT NULL" : "";
-    $defaultValue = (!is_null($column->getDefaultValue()) || !$column->notNull()) ? " DEFAULT " . $this->getValueDefinition($column->getDefaultValue()) : "";
+    $defaultValue = "";
+    if (!is_null($column->getDefaultValue()) || !$column->notNull()) {
+      $defaultValue = " DEFAULT " . $this->getValueDefinition($column->getDefaultValue());
+    }
+    
     return "`$columnName` $type$notNull$defaultValue";
   }
 
@@ -410,7 +394,6 @@ class MySQL extends SQL {
   }
 
   // TODO: check this please..
-  // TODO: Constants??
   public function getValueDefinition($value) {
     if (is_numeric($value) || is_bool($value)) {
       return $value;
@@ -424,6 +407,15 @@ class MySQL extends SQL {
     }
   }
 
+  protected function addValue($val, &$params) {
+    if ($val instanceof Keyword) {
+      return $val->getValue();
+    } else {
+      $params[] = $val;
+      return "?";
+    }
+  }
+
   public function currentTimestamp() {
     return "NOW()";
   }
diff --git a/core/Driver/SQL/PostgreSQL.class.php b/core/Driver/SQL/PostgreSQL.class.php
new file mode 100644
index 0000000..ca0d108
--- /dev/null
+++ b/core/Driver/SQL/PostgreSQL.class.php
@@ -0,0 +1,352 @@
+<?php
+
+namespace Driver\SQL;
+
+use \Api\Parameter\Parameter;
+
+use \Driver\SQL\Column\Column;
+use \Driver\SQL\Column\IntColumn;
+use \Driver\SQL\Column\SerialColumn;
+use \Driver\SQL\Column\StringColumn;
+use \Driver\SQL\Column\EnumColumn;
+use \Driver\SQL\Column\DateTimeColumn;
+use Driver\SQL\Column\BoolColumn;
+use Driver\SQL\Column\JsonColumn;
+
+use \Driver\SQL\Strategy\CascadeStrategy;
+use \Driver\SQL\Strategy\SetDefaultStrategy;
+use \Driver\SQL\Strategy\SetNullStrategy;
+use \Driver\SQL\Strategy\UpdateStrategy;
+
+use \Driver\SQL\Constraint\Unique;
+use \Driver\SQL\Constraint\PrimaryKey;
+use \Driver\SQL\Constraint\ForeignKey;
+
+class PostgreSQL extends SQL {
+
+  public function __construct($connectionData) {
+     parent::__construct($connectionData);
+  }
+
+  public function checkRequirements() {
+    return function_exists('pg_connect');
+  }
+
+  public function getDriverName() {
+    return 'pgsql';
+  }
+
+  public function getLastError() {
+    $lastError = parent::getLastError();
+    if (empty($lastError)) {
+      $lastError = pg_last_error($this->connection) . " " . pg_last_error($this->connection);
+    }
+
+    return $lastError;
+  }
+
+  // Connection Managment
+  public function connect() {
+    if(!is_null($this->connection)) {
+      return true;
+    }
+
+    $config = array(
+      "host" => $this->connectionData->getHost(),
+      "port" => $this->connectionData->getPort(),
+      "dbname" => $this->connectionData->getProperty('database', 'public'),
+      "user" => $this->connectionData->getLogin(),
+      "password" => $this->connectionData->getPassword()
+    );
+
+    $connectionString = array();
+    foreach($config as $key => $val) {
+      if (!empty($val)) {
+        $connectionString[] = "$key=$val";
+      }
+    }
+
+    $this->connection = @pg_connect(implode(" ", $connectionString));
+    if (!$this->connection) {
+      $this->lastError = "Failed to connect to Database";
+      $this->connection = NULL;
+      return false;
+    }
+
+    pg_set_client_encoding($this->connection, $this->connectionData->getProperty('encoding', 'UTF-8'));
+    return true;
+  }
+
+  public function disconnect() {
+    if(is_null($this->connection))
+      return;
+
+    pg_close($this->connection);
+  }
+
+  protected function execute($query, $values = NULL, $returnValues = false) {
+
+    $this->lastError = "";
+    $stmt_name = uniqid();
+    $pgParams = array();
+
+    if (!is_null($values)) {
+      foreach($values as $value) {
+        $paramType = Parameter::parseType($value);
+        switch($paramType) {
+          case Parameter::TYPE_DATE:
+            $value = $value->format("Y-m-d");
+            break;
+          case Parameter::TYPE_TIME:
+            $value = $value->format("H:i:s");
+            break;
+          case Parameter::TYPE_DATE_TIME:
+            $value = $value->format("Y-m-d H:i:s");
+            break;
+          default:
+            break;
+        }
+
+        $pgParams[] = $value;
+      }
+    }
+
+    $stmt = @pg_prepare($this->connection, $stmt_name, $query);
+    if ($stmt === FALSE) {
+      return false;
+    }
+
+    $result = @pg_execute($this->connection, $stmt_name, $pgParams);
+    if ($result === FALSE) {
+      return false;
+    }
+
+    if ($returnValues) {
+      $rows = pg_fetch_all($result);
+      if ($rows === FALSE) {
+        if (empty(trim($this->getLastError()))) {
+          $rows = array();
+        }
+      }
+
+      return $rows;
+    } else {
+      return true;
+    }
+  }
+
+  // Querybuilder
+  public function executeCreateTable($createTable) {
+    $tableName = $createTable->getTableName();
+    $ifNotExists = $createTable->ifNotExists() ? " IF NOT EXISTS": "";
+
+    $entries = array();
+    foreach($createTable->getColumns() as $column) {
+      $entries[] = ($tmp = $this->getColumnDefinition($column));
+      if (is_null($tmp)) {
+        return false;
+      }
+    }
+
+    foreach($createTable->getConstraints() as $constraint) {
+      $entries[] = ($tmp = $this->getConstraintDefinition($constraint));
+      if (is_null($tmp)) {
+        return false;
+      }
+    }
+
+    $entries = implode(",", $entries);
+    $query = "CREATE TABLE$ifNotExists \"$tableName\" ($entries)";
+    return $this->execute($query);
+  }
+
+  public function executeInsert($insert) {
+
+    $tableName = $insert->getTableName();
+    $columns = $insert->getColumns();
+    $rows = $insert->getRows();
+    $onDuplicateKey = $insert->onDuplicateKey() ?? "";
+
+    if (empty($rows)) {
+      $this->lastError = "No rows to insert given.";
+      return false;
+    }
+
+    if (is_null($columns) || empty($columns)) {
+      $columns = "";
+      $numColumns = count($rows[0]);
+    } else {
+      $numColumns = count($columns);
+      $columns = " (\"" . implode("\", \"", $columns) . "\")";
+    }
+
+    $numRows = count($rows);
+    $parameters = array();
+
+    $values = array();
+    foreach($rows as $row) {
+      $rowPlaceHolder = array();
+      foreach($row as $val) {
+        $rowPlaceHolder[] = $this->addValue($val, $parameters);
+      }
+
+      $values[] = "(" . implode(",", $rowPlaceHolder) . ")";
+    }
+
+    $values = implode(",", $values);
+
+    if ($onDuplicateKey) {
+      if ($onDuplicateKey instanceof UpdateStrategy) {
+        $updateValues = array();
+        foreach($onDuplicateKey->getValues() as $key => $value) {
+          if ($value instanceof Column) {
+            $columnName = $value->getName();
+            $updateValues[] = "\"$key\"=\"$columnName\"";
+          } else {
+            $updateValues[] = "\"$key\"=" . $this->addValue($value, $parameters);
+          }
+        }
+
+        $onDuplicateKey = " ON CONFLICT DO UPDATE SET " . implode(",", $updateValues);
+      } else {
+        $strategy = get_class($onDuplicateKey);
+        $this->lastError = "ON DUPLICATE Strategy $strategy is not supported yet.";
+        return false;
+      }
+    }
+
+    $returningCol = $insert->getReturning();
+    $returning = $returningCol ? " RETURNING \"$returningCol\"" : "";
+
+    $query = "INSERT INTO \"$tableName\"$columns VALUES$values$onDuplicateKey$returning";
+    $res = $this->execute($query, $parameters, !empty($returning));
+    $success = ($res !== FALSE);
+
+    if($success && !empty($returning)) {
+      $this->lastInsertId = $res[0][$returningCol];
+    }
+
+    return $success;
+  }
+
+  // TODO:
+  public function executeSelect($query) { }
+  public function executeDelete($query) { }
+  public function executeTruncate($query) { }
+  public function executeUpdate($query) { }
+
+  // UGLY but.. what should i do?
+  private function createEnum($enumColumn) {
+    $typeName = $enumColumn->getName();
+    if(!endsWith($typeName, "_type")) {
+      $typeName = "${typeName}_type";
+    }
+
+    $values = array();
+    foreach($enumColumn->getValues() as $value) {
+      $values[] = $this->getValueDefinition($value);
+    }
+
+    $values = implode(",", $values);
+    $query =
+      "DO $$ BEGIN
+        CREATE TYPE \"$typeName\" AS ENUM ($values);
+      EXCEPTION
+        WHEN duplicate_object THEN null;
+      END $$;";
+
+    $this->execute($query);
+    return $typeName;
+  }
+
+  protected function getColumnDefinition($column) {
+    $columnName = $column->getName();
+
+    if ($column instanceof StringColumn) {
+      $maxSize = $column->getMaxSize();
+      if ($maxSize) {
+        $type = "VARCHAR($maxSize)";
+      } else {
+        $type = "TEXT";
+      }
+    } else if($column instanceof SerialColumn) {
+      $type = "SERIAL";
+    } else if($column instanceof IntColumn) {
+      $type = "INTEGER";
+    } else if($column instanceof DateTimeColumn) {
+      $type = "TIMESTAMP";
+    } else if($column instanceof EnumColumn) {
+      $type = $this->createEnum($column);
+    } else if($column instanceof BoolColumn) {
+      $type = "BOOLEAN";
+    } else if($column instanceof JsonColumn) {
+      $type = "JSON";
+    } else {
+      $this->lastError = "Unsupported Column Type: " . get_class($column);
+      return NULL;
+    }
+
+    $notNull = $column->notNull() ? " NOT NULL" : "";
+    $defaultValue = "";
+    if (!is_null($column->getDefaultValue()) || !$column->notNull()) {
+      $defaultValue = " DEFAULT " . $this->getValueDefinition($column->getDefaultValue());
+    }
+
+    return "\"$columnName\" $type$notNull$defaultValue";
+  }
+
+  protected function getConstraintDefinition($constraint) {
+    $columnName = $constraint->getColumnName();
+    if ($constraint instanceof PrimaryKey) {
+      if (is_array($columnName)) $columnName = implode('","', $columnName);
+      return "PRIMARY KEY (\"$columnName\")";
+    } else if ($constraint instanceof Unique) {
+      if (is_array($columnName)) $columnName = implode('","', $columnName);
+      return "UNIQUE (\"$columnName\")";
+    } else if ($constraint instanceof ForeignKey) {
+      $refTable = $constraint->getReferencedTable();
+      $refColumn = $constraint->getReferencedColumn();
+      $strategy = $constraint->onDelete();
+      $code = "FOREIGN KEY (\"$columnName\") REFERENCES \"$refTable\" (\"$refColumn\")";
+      if ($strategy instanceof SetDefaultStrategy) {
+        $code .= " ON DELETE SET DEFAULT";
+      } else if($strategy instanceof SetNullStrategy) {
+        $code .= " ON DELETE SET NULL";
+      } else if($strategy instanceof CascadeStrategy) {
+        $code .= " ON DELETE CASCADE";
+      }
+
+      return $code;
+    }
+  }
+
+  protected function getValueDefinition($value) {
+    if (is_numeric($value)) {
+      return $value;
+    } else if(is_bool($value)) {
+      return $value ? "TRUE" : "FALSE";
+    } else if(is_null($value)) {
+      return "NULL";
+    } else if($value instanceof Keyword) {
+      return $value->getValue();
+    } else {
+      $str = str_replace("'", "''", $value);
+      return "'$str'";
+    }
+  }
+
+  protected function addValue($val, &$params) {
+    if ($val instanceof Keyword) {
+      return $val->getValue();
+    } else {
+      $params[] = $val;
+      return '$' . count($params);
+    }
+  }
+
+  // Special Keywords and functions
+  public function currentTimestamp() {
+    return "CURRENT_TIMESTAMP";
+  }
+}
+?>
diff --git a/core/Driver/SQL/Query/CreateTable.class.php b/core/Driver/SQL/Query/CreateTable.class.php
index 77116de..9de7708 100644
--- a/core/Driver/SQL/Query/CreateTable.class.php
+++ b/core/Driver/SQL/Query/CreateTable.class.php
@@ -39,8 +39,8 @@ class CreateTable extends Query {
     return $this;
   }
 
-  public function addDateTime($name, $nullable=false, $defaultNow=false) {
-    $this->columns[$name] = new DateTimeColumn($name, $nullable, $defaultNow);
+  public function addDateTime($name, $nullable=false, $defaultValue=NULL) {
+    $this->columns[$name] = new DateTimeColumn($name, $nullable, $defaultValue);
     return $this;
   }
 
diff --git a/core/Driver/SQL/Query/Insert.class.php b/core/Driver/SQL/Query/Insert.class.php
index b6145dd..34350a7 100644
--- a/core/Driver/SQL/Query/Insert.class.php
+++ b/core/Driver/SQL/Query/Insert.class.php
@@ -8,6 +8,7 @@ class Insert extends Query {
   private $columns;
   private $rows;
   private $onDuplicateKey;
+  private $returning;
 
   public function __construct($sql, $name, $columns=array()) {
     parent::__construct($sql);
@@ -15,6 +16,7 @@ class Insert extends Query {
     $this->columns = $columns;
     $this->rows = array();
     $this->onDuplicateKey = NULL;
+    $this->returning = NULL;
   }
 
   public function addRow(...$values) {
@@ -27,6 +29,11 @@ class Insert extends Query {
     return $this;
   }
 
+  public function returning($column) {
+    $this->returning = $column;
+    return $this;
+  }
+
   public function execute() {
     return $this->sql->executeInsert($this);
   }
@@ -35,6 +42,7 @@ class Insert extends Query {
   public function getColumns() { return $this->columns; }
   public function getRows() { return $this->rows; }
   public function onDuplicateKey() { return $this->onDuplicateKey; }
+  public function getReturning() { return $this->returning; }
 };
 
 ?>
diff --git a/core/Driver/SQL/SQL.class.php b/core/Driver/SQL/SQL.class.php
index ff4b47a..9529a9e 100644
--- a/core/Driver/SQL/SQL.class.php
+++ b/core/Driver/SQL/SQL.class.php
@@ -8,19 +8,14 @@ abstract class SQL {
   protected $connection;
   protected $connectionData;
   protected $lastInsertId;
-  private $type;
 
-  public function __construct($type, $connectionData) {
-    $this->type = $type;
+  public function __construct($connectionData) {
     $this->connection = NULL;
     $this->lastError = 'Not connected';
     $this->connectionData = $connectionData;
     $this->lastInsertId = 0;
   }
 
-  public abstract function connect();
-  public abstract function disconnect();
-
   public function isConnected() {
     return !is_null($this->connection);
   }
@@ -29,17 +24,6 @@ abstract class SQL {
     return trim($this->lastError);
   }
 
-  // public function executeQuery($query) {
-  //   if(!$this->isConnected()) {
-  //     $this->lastError = "Database is not connected yet.";
-  //     return false;
-  //   }
-  //
-  //   return $query->execute($this);
-  //   // var_dump($generatedQuery);
-  //   // return $this->execute($generatedQuery);
-  // }
-
   public function createTable($tableName) {
     return new Query\CreateTable($this, $tableName);
   }
@@ -64,6 +48,18 @@ abstract class SQL {
     return new Query\Update($this, $table);
   }
 
+  // ####################
+  // ### ABSTRACT METHODS
+  // ####################
+
+  // Misc
+  public abstract function checkRequirements();
+  public abstract function getDriverName();
+
+  // Connection Managment
+  public abstract function connect();
+  public abstract function disconnect();
+
   // Querybuilder
   public abstract function executeCreateTable($query);
   public abstract function executeInsert($query);
@@ -71,114 +67,74 @@ abstract class SQL {
   public abstract function executeDelete($query);
   public abstract function executeTruncate($query);
   public abstract function executeUpdate($query);
-
-  //
-  public abstract function currentTimestamp();
-
   protected abstract function getColumnDefinition($column);
   protected abstract function getConstraintDefinition($constraint);
   protected abstract function getValueDefinition($val);
-  protected abstract function buildCondition($conditions, &$params);
+  protected abstract function addValue($val, &$params);
 
-  // Execute
+  // Special Keywords and functions
+  public abstract function currentTimestamp();
+
+  // Statements
   protected abstract function execute($query, $values=NULL, $returnValues=false);
 
+  protected function buildCondition($condition, &$params) {
+    if ($condition instanceof \Driver\SQL\Condition\CondOr) {
+      $conditions = array();
+      foreach($condition->getConditions() as $cond) {
+        $conditions[] = $this->buildCondition($cond, $params);
+      }
+      return "(" . implode(" OR ", $conditions) . ")";
+    } else if ($condition instanceof \Driver\SQL\Condition\Compare) {
+      $column = $condition->getColumn();
+      $value = $condition->getValue();
+      $operator = $condition->getOperator();
+      return $column . $operator . $this->addValue($value, $params);
+    } else if ($condition instanceof \Driver\SQL\Condition\CondBool) {
+      return $condition->getValue();
+    } else if (is_array($condition)) {
+      if (count($condition) == 1) {
+        return $this->buildCondition($condition[0], $params);
+      } else {
+        $conditions = array();
+        foreach($condition as $cond) {
+          $conditions[] = $this->buildCondition($cond, $params);
+        }
+        return implode(" AND ", $conditions);
+      }
+    }
+  }
+
   public function setLastError($str) {
     $this->lastError = $str;
   }
 
-  protected function addValue($val, &$params) {
-    if ($val instanceof Keyword) {
-      return $val->getValue();
-    } else {
-      $params[] = $val;
-      return "?";
-    }
-  }
-
-  /*public function getLastErrorNumber() {
-    return mysqli_errno($this->connection);
-  }*/
-
   public function getLastInsertId() {
     return $this->lastInsertId;
   }
 
   public function close() {
-    if(!is_null($this->connection)) {
-      $this->connection->close();
-    }
+    $this->disconnect();
+    $this->connection = NULL;
   }
 
-  /*public function getAffectedRows() {
-    return $this->connection->affected_rows;
-  }*/
-
-  /*
-  public function execute($query) {
-    if(!$this->isConnected()) {
-      return false;
-    }
-
-    if(!mysqli_query($this->connection, $query)) {
-      $this->lastError = mysqli_error($this->connection);
-      return false;
-    }
-
-    return true;
-  }
-
-  public function executeMulti($queries) {
-    if(!$this->isConnected()) {
-      return false;
-    }
-
-    if(!$this->connection->multi_query($queries)) {
-      $this->lastError = mysqli_error($this->connection);
-      return false;
-    }
-
-    while (($success = $this->connection->next_result())) {
-      if (!$this->connection->more_results()) break;
-    }
-
-    if(!$success) {
-      $this->lastError = mysqli_error($this->connection);
-      return false;
-    }
-
-    return true;
-  }
-
-  public function query($query) {
-    if(!$this->isConnected()) {
-      return false;
-    }
-
-    $res = mysqli_query($this->connection, $query);
-    if(!$res) {
-      $this->lastError = mysqli_error($this->connection);
-      return false;
-    }
-
-    return $res;
-  }
-  */
-
   public static function createConnection($connectionData) {
     $type = $connectionData->getProperty("type");
     if ($type === "mysql") {
       $sql = new MySQL($connectionData);
-    /*} else if ($type === "postgres") {
-      // $sql = new PostgreSQL($connectionData);
-    } else if ($type === "oracle") {
+    } else if ($type === "postgres") {
+      $sql = new PostgreSQL($connectionData);
+    /*} else if ($type === "oracle") {
       // $sql = new OracleSQL($connectionData);
     */
     } else {
       return "Unknown database type";
     }
 
-    $sql->connect();
+    if ($sql->checkRequirements()) {
+      $sql->connect();
+    }
+
     return $sql;
   }
 }
diff --git a/core/Objects/ConnectionData.class.php b/core/Objects/ConnectionData.class.php
index 0b845f9..e6a59c8 100644
--- a/core/Objects/ConnectionData.class.php
+++ b/core/Objects/ConnectionData.class.php
@@ -22,11 +22,8 @@ class ConnectionData {
     return $this->properties;
   }
 
-  public function getProperty($key) {
-    if(isset($this->properties[$key]))
-      return $this->properties[$key];
-    else
-      return '';
+  public function getProperty($key, $defaultValue='') {
+    return $this->properties[$key] ?? $defaultValue;
   }
 
   public function setProperty($key, $val) {
diff --git a/core/Objects/Session.class.php b/core/Objects/Session.class.php
index 5a54ede..3ac560a 100644
--- a/core/Objects/Session.class.php
+++ b/core/Objects/Session.class.php
@@ -101,6 +101,7 @@ class Session extends ApiObject {
         $this->browser,
         json_encode($_SESSION),
         $stayLoggedIn)
+      ->returning("uid")
       ->execute();
 
     if($success) {
diff --git a/js/install.js b/js/install.js
index f27ef29..ec661ec 100644
--- a/js/install.js
+++ b/js/install.js
@@ -78,13 +78,15 @@ $(document).ready(function() {
     var textBefore = $("#btnSubmit").text();
     $("#btnSubmit").prop("disabled", true);
     $("#btnSubmit").html("Submitting… <i class=\"fas fa-spinner fa-spin\">");
-    $("#installForm input").each(function() {
-      var type = $(this).attr("type");
+    $("#installForm .form-control").each(function() {
+      var type = $(this).attr("type") ?? $(this).prop("tagName").toLowerCase();
       var name = $(this).attr("name");
       if(type === "text") {
         params[name] = $(this).val().trim();
       } else if(type === "password" || type === "number") {
         params[name] = $(this).val();
+      } else if(type === "select") {
+        params[name] = $(this).find(":selected").val();
       }
     }).promise().done(function() {
       sendRequest(params, function(success) {
@@ -128,4 +130,24 @@ $(document).ready(function() {
     retry();
   });
 
+  // DATABASE PORT
+  var prevPort = $("#port").val();
+  var prevDbms = $("#type option:selected").val();
+  function updateDefaultPort() {
+    var defaultPorts = {
+      "mysql": 3306,
+      "postgres": 5432,
+      "oracle": 1521
+    };
+
+    var curDbms = $("#type option:selected").val();
+    if(defaultPorts[prevDbms] == prevPort) {
+      $("#port").val(defaultPorts[curDbms]);
+    }
+  }
+
+  updateDefaultPort();
+  $("#type").change(function() {
+    updateDefaultPort();
+  });
 });