diff --git a/src/ColumnDisplayFormatDialog.cpp b/src/ColumnDisplayFormatDialog.cpp
index da62c6d59..506cd3fa9 100644
--- a/src/ColumnDisplayFormatDialog.cpp
+++ b/src/ColumnDisplayFormatDialog.cpp
@@ -1,11 +1,16 @@
+#include <QMessageBox>
+
 #include "ColumnDisplayFormatDialog.h"
 #include "ui_ColumnDisplayFormatDialog.h"
 #include "sql/sqlitetypes.h"
+#include "sqlitedb.h"
 
-ColumnDisplayFormatDialog::ColumnDisplayFormatDialog(const QString& colname, QString current_format, QWidget* parent)
+ColumnDisplayFormatDialog::ColumnDisplayFormatDialog(DBBrowserDB& db, const sqlb::ObjectIdentifier& tableName, const QString& colname, QString current_format, QWidget* parent)
     : QDialog(parent),
       ui(new Ui::ColumnDisplayFormatDialog),
-      column_name(colname)
+      column_name(colname),
+      pdb(db),
+      curTable(tableName)
 {
     // Create UI
     ui->setupUi(this);
@@ -28,6 +33,9 @@ ColumnDisplayFormatDialog::ColumnDisplayFormatDialog(const QString& colname, QSt
     ui->comboDisplayFormat->insertSeparator(ui->comboDisplayFormat->count());
     ui->comboDisplayFormat->addItem(tr("Lower case"), "lower");
     ui->comboDisplayFormat->addItem(tr("Upper case"), "upper");
+    ui->comboDisplayFormat->insertSeparator(ui->comboDisplayFormat->count());
+    ui->comboDisplayFormat->addItem(tr("Custom"), "custom");
+
     ui->labelDisplayFormat->setText(ui->labelDisplayFormat->text().arg(column_name));
 
     formatFunctions["decimal"] = "printf('%d', " + sqlb::escapeIdentifier(column_name) + ")";
@@ -53,19 +61,14 @@ ColumnDisplayFormatDialog::ColumnDisplayFormatDialog(const QString& colname, QSt
         ui->comboDisplayFormat->setCurrentIndex(0);
         updateSqlCode();
     } else {
-        QString formatName;
+        // When it doesn't match any predefined format, it is considered custom
+        QString formatName = "custom";
         for(auto& formatKey : formatFunctions.keys()) {
             if(current_format == formatFunctions.value(formatKey)) {
                 formatName = formatKey;
                 break;
             }
         }
-
-        if(formatName.isEmpty()) {
-            ui->comboDisplayFormat->insertSeparator(ui->comboDisplayFormat->count());
-            ui->comboDisplayFormat->addItem(tr("Custom"), "custom");
-            formatName = "custom";
-        }
         ui->comboDisplayFormat->setCurrentIndex(ui->comboDisplayFormat->findData(formatName));
         ui->editDisplayFormat->setText(current_format);
     }
@@ -90,7 +93,46 @@ void ColumnDisplayFormatDialog::updateSqlCode()
 
     if(format == "default")
         ui->editDisplayFormat->setText(sqlb::escapeIdentifier(column_name));
-    else
+    else if(format != "custom")
         ui->editDisplayFormat->setText(formatFunctions.value(format));
+}
+
+void ColumnDisplayFormatDialog::accept()
+{
+    QString errorMessage;
+
+    // Accept the SQL code if it's the column name (default), it contains a function invocation applied to the column name and it can be
+    // executed without errors returning only one column.
+    // Users could still devise a way to break this, but this is considered good enough for letting them know about simple incorrect
+    // cases.
+    if(!(ui->editDisplayFormat->text() == sqlb::escapeIdentifier(column_name) ||
+         ui->editDisplayFormat->text().contains(QRegExp("[a-z]+[a-z_0-9]* *\\(.*" + QRegExp::escape(sqlb::escapeIdentifier(column_name)) + ".*\\)", Qt::CaseInsensitive))))
+        errorMessage = tr("Custom display format must contain a function call applied to %1").arg(sqlb::escapeIdentifier(column_name));
+    else {
+        // Execute a query using the display format and check that it only returns one column.
+        int customNumberColumns = 0;
+
+        DBBrowserDB::execCallback callback = [&customNumberColumns](int numberColumns, QStringList, QStringList) -> bool {
+            customNumberColumns = numberColumns;
+            // Return false so the query is not aborted and no error is reported.
+            return false;
+        };
+        if(!pdb.executeSQL(QString("SELECT %1 FROM %2 LIMIT 1").arg(ui->editDisplayFormat->text(), curTable.toString()),
+                           false, true, callback))
+            errorMessage = tr("Error in custom display format. Message from database engine:\n\n%1").arg(pdb.lastError());
+        else if(customNumberColumns != 1)
+            errorMessage = tr("Custom display format must return only one column but it returned %1.").arg(customNumberColumns);
+
+    }
+    if(!errorMessage.isEmpty())
+        QMessageBox::warning(this, QApplication::applicationName(), errorMessage);
+    else
+        QDialog::accept();
+}
 
+void ColumnDisplayFormatDialog::setCustom(bool modified)
+{
+    // If the SQL code is modified by user, select the custom value in the combo-box
+    if(modified && ui->editDisplayFormat->hasFocus())
+        ui->comboDisplayFormat->setCurrentIndex(ui->comboDisplayFormat->findData("custom"));
 }
diff --git a/src/ColumnDisplayFormatDialog.h b/src/ColumnDisplayFormatDialog.h
index 4cf2d0bfe..dad8d575a 100644
--- a/src/ColumnDisplayFormatDialog.h
+++ b/src/ColumnDisplayFormatDialog.h
@@ -5,6 +5,10 @@
 #include <QString>
 #include <QMap>
 
+#include "sql/sqlitetypes.h"
+
+class DBBrowserDB;
+
 namespace Ui {
 class ColumnDisplayFormatDialog;
 }
@@ -14,18 +18,22 @@ class ColumnDisplayFormatDialog : public QDialog
     Q_OBJECT
 
 public:
-    explicit ColumnDisplayFormatDialog(const QString& colname, QString current_format, QWidget* parent = nullptr);
+    explicit ColumnDisplayFormatDialog(DBBrowserDB& db, const sqlb::ObjectIdentifier& tableName, const QString& colname, QString current_format, QWidget* parent = nullptr);
     ~ColumnDisplayFormatDialog() override;
 
     QString selectedDisplayFormat() const;
 
 private slots:
     void updateSqlCode();
+    void accept() override;
+    void setCustom(bool modified);
 
 private:
     Ui::ColumnDisplayFormatDialog* ui;
     QString column_name;
     QMap<QString, QString> formatFunctions;
+    DBBrowserDB& pdb;
+    sqlb::ObjectIdentifier curTable;
 };
 
 #endif
diff --git a/src/ColumnDisplayFormatDialog.ui b/src/ColumnDisplayFormatDialog.ui
index 20844213b..5816b8b05 100644
--- a/src/ColumnDisplayFormatDialog.ui
+++ b/src/ColumnDisplayFormatDialog.ui
@@ -31,11 +31,7 @@
        <widget class="QComboBox" name="comboDisplayFormat"/>
       </item>
       <item>
-       <widget class="SqlTextEdit" name="editDisplayFormat">
-        <property name="readOnly">
-         <bool>true</bool>
-        </property>
-       </widget>
+       <widget class="SqlTextEdit" name="editDisplayFormat"/>
       </item>
      </layout>
     </widget>
@@ -114,8 +110,25 @@
     </hint>
    </hints>
   </connection>
+  <connection>
+   <sender>editDisplayFormat</sender>
+   <signal>modificationChanged(bool)</signal>
+   <receiver>ColumnDisplayFormatDialog</receiver>
+   <slot>setCustom(bool)</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>125</x>
+     <y>69</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>244</x>
+     <y>4</y>
+    </hint>
+   </hints>
+  </connection>
  </connections>
  <slots>
   <slot>updateSqlCode()</slot>
+  <slot>setCustom()</slot>
  </slots>
 </ui>
diff --git a/src/MainWindow.cpp b/src/MainWindow.cpp
index 066bba789..88e69e39f 100644
--- a/src/MainWindow.cpp
+++ b/src/MainWindow.cpp
@@ -3350,7 +3350,7 @@ void MainWindow::editDataColumnDisplayFormat()
     QString current_displayformat = browseTableSettings[current_table].displayFormats[field_number];
 
     // Open the dialog
-    ColumnDisplayFormatDialog dialog(field_name, current_displayformat, this);
+    ColumnDisplayFormatDialog dialog(db, current_table, field_name, current_displayformat, this);
     if(dialog.exec())
     {
         // Set the newly selected display format
diff --git a/src/sqlitedb.cpp b/src/sqlitedb.cpp
index 398973bfe..86c91fef1 100644
--- a/src/sqlitedb.cpp
+++ b/src/sqlitedb.cpp
@@ -890,7 +890,23 @@ bool DBBrowserDB::dump(const QString& filePath,
     return false;
 }
 
-bool DBBrowserDB::executeSQL(QString statement, bool dirtyDB, bool logsql)
+// Callback for sqlite3_exec. It receives the user callback in the first parameter. Converts parameters
+// to C++ classes and calls user callback.
+int DBBrowserDB::callbackWrapper (void* callback, int numberColumns, char** values, char** columnNames)
+{
+    QStringList valuesList;
+    QStringList namesList;
+
+    for (int i=0; i<numberColumns; i++) {
+        valuesList << QString(values[i]);
+        namesList << QString(columnNames[i]);
+    }
+
+    execCallback userCallback = *(static_cast<execCallback*>(callback));
+    return userCallback(numberColumns, valuesList, namesList);
+}
+
+bool DBBrowserDB::executeSQL(QString statement, bool dirtyDB, bool logsql, execCallback callback)
 {
     waitForDbRelease();
     if(!_db)
@@ -905,7 +921,7 @@ bool DBBrowserDB::executeSQL(QString statement, bool dirtyDB, bool logsql)
     if (dirtyDB) setSavepoint();
 
     char* errmsg;
-    if (SQLITE_OK == sqlite3_exec(_db, statement.toUtf8(), nullptr, nullptr, &errmsg))
+    if (SQLITE_OK == sqlite3_exec(_db, statement.toUtf8(), callback ? callbackWrapper : nullptr, &callback, &errmsg))
     {
         // Update DB structure after executing an SQL statement. But try to avoid doing unnecessary updates.
         if(!dontCheckForStructureUpdates && (statement.startsWith("ALTER", Qt::CaseInsensitive) ||
@@ -919,6 +935,7 @@ bool DBBrowserDB::executeSQL(QString statement, bool dirtyDB, bool logsql)
         lastErrorMessage = QString("%1 (%2)").arg(QString::fromUtf8(errmsg)).arg(statement);
         qWarning() << "executeSQL: " << statement << "->" << errmsg;
         sqlite3_free(errmsg);
+
         return false;
     }
 }
diff --git a/src/sqlitedb.h b/src/sqlitedb.h
index 19ae4f409..d50cb7d3a 100644
--- a/src/sqlitedb.h
+++ b/src/sqlitedb.h
@@ -6,6 +6,7 @@
 #include <condition_variable>
 #include <memory>
 #include <mutex>
+#include <functional>
 
 #include <QByteArray>
 #include <QMultiMap>
@@ -54,6 +55,7 @@ class DBBrowserDB : public QObject
     };
 
 public:
+
     explicit DBBrowserDB () : _db(nullptr), db_used(false), isEncrypted(false), isReadOnly(false), dontCheckForStructureUpdates(false) {}
     ~DBBrowserDB () override {}
 
@@ -104,8 +106,17 @@ class DBBrowserDB : public QObject
         Wait,
         CancelOther
     };
-
-    bool executeSQL(QString statement, bool dirtyDB = true, bool logsql = true);
+    // Callback to get results from executeSQL(). It is invoked for
+    // each result row coming out of the evaluated SQL statements. If
+    // a callback returns true (abort), the executeSQL() method
+    // returns false (error) without invoking the callback again and
+    // without running any subsequent SQL statements. The 1st argument
+    // is the number of columns in the result. The 2nd argument to the
+    // callback is the text representation of the values, one for each
+    // column. The 3rd argument is a list of strings where each entry
+    // represents the name of corresponding result column.
+    typedef std::function<bool(int, QStringList, QStringList)> execCallback;
+    bool executeSQL(QString statement, bool dirtyDB = true, bool logsql = true, execCallback callback = nullptr);
     bool executeMultiSQL(QByteArray query, bool dirty = true, bool log = false);
     QByteArray querySingleValueFromDb(const QString& sql, bool log = true, ChoiceOnUse choice = Ask);
 
@@ -136,6 +147,8 @@ class DBBrowserDB : public QObject
      */
     QString max(const sqlb::ObjectIdentifier& tableName, const sqlb::Field& field) const;
 
+    static int callbackWrapper (void* callback, int numberColumns, char** values, char** columnNames);
+
 public:
     void updateSchema();