diff --git a/lib/dialects/oracledb/index.js b/lib/dialects/oracledb/index.js
index 40b70085..a41c8e72 100644
--- a/lib/dialects/oracledb/index.js
+++ b/lib/dialects/oracledb/index.js
@@ -81,6 +81,24 @@ Client_Oracledb.prototype.prepBindings = function (bindings) {
   });
 };
 
+function resolveConnectString(connectionSettings) {
+  if (connectionSettings.connectString) {
+    return connectionSettings.connectString;
+  }
+
+  if (!connectionSettings.port) {
+    return connectionSettings.host + '/' + connectionSettings.database;
+  }
+
+  return (
+    connectionSettings.host +
+    ':' +
+    connectionSettings.port +
+    '/' +
+    connectionSettings.database
+  );
+}
+
 // Get a raw connection, called by the `pool` whenever a new
 // connection needs to be added to the pool.
 Client_Oracledb.prototype.acquireRawConnection = function () {
@@ -96,9 +114,9 @@ Client_Oracledb.prototype.acquireRawConnection = function () {
         };
 
     // In the case of external authentication connection string will be given
-    oracleDbConfig.connectString =
-      client.connectionSettings.connectString ||
-      client.connectionSettings.host + '/' + client.connectionSettings.database;
+    oracleDbConfig.connectString = resolveConnectString(
+      client.connectionSettings
+    );
 
     if (client.connectionSettings.prefetchRowCount) {
       oracleDbConfig.prefetchRows = client.connectionSettings.prefetchRowCount;
@@ -142,60 +160,68 @@ Client_Oracledb.prototype.acquireRawConnection = function () {
           throw new Error('not found oracledb.outFormat constants');
         }
         if (options.resultSet) {
-          connection.execute(sql, bindParams || [], options, function (
-            err,
-            result
-          ) {
-            if (err) {
-              if (isConnectionError(err)) {
-                connection.close().catch(function (err) {});
-                connection.__knex__disposed = err;
-              }
-              return cb(err);
-            }
-            const fetchResult = { rows: [], resultSet: result.resultSet };
-            const numRows = 100;
-            const fetchRowsFromRS = function (connection, resultSet, numRows) {
-              resultSet.getRows(numRows, function (err, rows) {
-                if (err) {
-                  if (isConnectionError(err)) {
-                    connection.close().catch(function (err) {});
-                    connection.__knex__disposed = err;
-                  }
-                  resultSet.close(function () {
-                    return cb(err);
-                  });
-                } else if (rows.length === 0) {
-                  return cb(null, fetchResult);
-                } else if (rows.length > 0) {
-                  if (rows.length === numRows) {
-                    fetchResult.rows = fetchResult.rows.concat(rows);
-                    fetchRowsFromRS(connection, resultSet, numRows);
-                  } else {
-                    fetchResult.rows = fetchResult.rows.concat(rows);
-                    return cb(null, fetchResult);
-                  }
+          connection.execute(
+            sql,
+            bindParams || [],
+            options,
+            function (err, result) {
+              if (err) {
+                if (isConnectionError(err)) {
+                  connection.close().catch(function (err) {});
+                  connection.__knex__disposed = err;
                 }
-              });
-            };
-            fetchRowsFromRS(connection, result.resultSet, numRows);
-          });
-        } else {
-          connection.execute(sql, bindParams || [], options, function (
-            err,
-            result
-          ) {
-            if (err) {
-              // dispose the connection on connection error
-              if (isConnectionError(err)) {
-                connection.close().catch(function (err) {});
-                connection.__knex__disposed = err;
+                return cb(err);
               }
-              return cb(err);
+              const fetchResult = { rows: [], resultSet: result.resultSet };
+              const numRows = 100;
+              const fetchRowsFromRS = function (
+                connection,
+                resultSet,
+                numRows
+              ) {
+                resultSet.getRows(numRows, function (err, rows) {
+                  if (err) {
+                    if (isConnectionError(err)) {
+                      connection.close().catch(function (err) {});
+                      connection.__knex__disposed = err;
+                    }
+                    resultSet.close(function () {
+                      return cb(err);
+                    });
+                  } else if (rows.length === 0) {
+                    return cb(null, fetchResult);
+                  } else if (rows.length > 0) {
+                    if (rows.length === numRows) {
+                      fetchResult.rows = fetchResult.rows.concat(rows);
+                      fetchRowsFromRS(connection, resultSet, numRows);
+                    } else {
+                      fetchResult.rows = fetchResult.rows.concat(rows);
+                      return cb(null, fetchResult);
+                    }
+                  }
+                });
+              };
+              fetchRowsFromRS(connection, result.resultSet, numRows);
             }
+          );
+        } else {
+          connection.execute(
+            sql,
+            bindParams || [],
+            options,
+            function (err, result) {
+              if (err) {
+                // dispose the connection on connection error
+                if (isConnectionError(err)) {
+                  connection.close().catch(function (err) {});
+                  connection.__knex__disposed = err;
+                }
+                return cb(err);
+              }
 
-            return cb(null, result);
-          });
+              return cb(null, result);
+            }
+          );
         }
       });
       connection.executeAsync = function (sql, bindParams, options) {