diff --git a/adminer/include/adminer.inc.php b/adminer/include/adminer.inc.php
index d887cd4c..277e4fbe 100644
--- a/adminer/include/adminer.inc.php
+++ b/adminer/include/adminer.inc.php
@@ -751,7 +751,7 @@ class Adminer {
 	* @param string
 	* @return string custom input field or empty string for default
 	*/
-	function editInput($table, $field, $attrs, $value) {
+	function editInput($table, $field, $attrs, $value, $function) {
 		if ($field["type"] == "enum") {
 			return (isset($_GET["select"]) ? "<label><input type='radio'$attrs value='-1' checked><i>" . lang('original') . "</i></label> " : "")
 				. ($field["null"] ? "<label><input type='radio'$attrs value=''" . ($value !== null || isset($_GET["select"]) ? "" : " checked") . "><i>NULL</i></label> " : "")
diff --git a/adminer/include/functions.inc.php b/adminer/include/functions.inc.php
index 692c3c94..9f5cb210 100644
--- a/adminer/include/functions.inc.php
+++ b/adminer/include/functions.inc.php
@@ -963,7 +963,7 @@ function input($field, $value, $function) {
 	echo "<td class='function'>";
 
 	if ($field["type"] == "enum") {
-		echo h($functions[""]) . "<td>" . $adminer->editInput($_GET["edit"], $field, $attrs, $value);
+		echo h($functions[""]) . "<td>" . $adminer->editInput($_GET["edit"], $field, $attrs, $value, $function);
 	} else {
 		$has_function = (in_array($function, $functions) || isset($functions[$function]));
 		echo (count($functions) > 1
@@ -972,7 +972,7 @@ function input($field, $value, $function) {
 				. script("qsl('select').onchange = functionChange;", "")
 			: h(reset($functions))
 		) . '<td>';
-		$input = $adminer->editInput($_GET["edit"], $field, $attrs, $value); // usage in call is without a table
+		$input = $adminer->editInput($_GET["edit"], $field, $attrs, $value, $function); // usage in call is without a table
 		if ($input != "") {
 			echo $input;
 		} elseif (preg_match('~bool~', $field["type"])) {
@@ -1006,7 +1006,8 @@ function input($field, $value, $function) {
 			// type='date' and type='time' display localized value which may be confusing, type='datetime' uses 'T' as date and time separator
 			echo "<input"
 				. ((!$has_function || $function === "") && preg_match('~(?<!o)int(?!er)~', $field["type"]) && !preg_match('~\[\]~', $field["full_type"]) ? " type='number'" : "")
-				. " value='" . h($value) . "'" . ($maxlength ? " data-maxlength='$maxlength'" : "")
+				. ($function != "now" ? " value='" . h($value) . "'" : " data-last-value='" . h($value) . "'")
+				. ($maxlength ? " data-maxlength='$maxlength'" : "")
 				. (preg_match('~char|binary~', $field["type"]) && $maxlength > 20 ? " size='40'" : "")
 				. "$attrs>"
 			;
@@ -1020,9 +1021,7 @@ function input($field, $value, $function) {
 			}
 			$first++;
 		}
-		if ($first) {
-			echo script("mixin(qsl('td'), {onchange: partial(skipOriginal, $first), oninput: function () { this.onchange(); }});");
-		}
+		echo script("mixin(qsl('td'), {onchange: partial(skipOriginal, $first), oninput: function () { this.onchange(); }});");
 	}
 }
 
diff --git a/adminer/static/functions.js b/adminer/static/functions.js
index c5d8107f..5f62992d 100644
--- a/adminer/static/functions.js
+++ b/adminer/static/functions.js
@@ -547,37 +547,62 @@ function editingKeydown(event) {
 	return true;
 }
 
-/** Disable maxlength for functions
-* @this HTMLSelectElement
-*/
+/**
+ * Disables maxlength for functions and manages value visibility.
+ *
+ * @this HTMLSelectElement
+ */
 function functionChange() {
-	var input = this.form[this.name.replace(/^function/, 'fields')];
-	if (input) { // undefined with the set data type
-		if (selectValue(this)) {
-			if (input.origType === undefined) {
-				input.origType = input.type;
-				input.origMaxLength = input.getAttribute('data-maxlength');
-			}
-			input.removeAttribute('data-maxlength');
-			input.type = 'text';
-		} else if (input.origType) {
-			input.type = input.origType;
-			if (input.origMaxLength >= 0) {
-				input.setAttribute('data-maxlength', input.origMaxLength);
-			}
-		}
-		oninput({target: input});
+	const input = this.form[this.name.replace(/^function/, 'fields')];
+	const value = selectValue(this);
+
+	// Undefined with the set data type.
+	if (!input) {
+		helpClose();
+		return;
 	}
+
+	if (value) {
+		if (input.origType === undefined) {
+			input.origType = input.type;
+			input.origMaxLength = input.getAttribute('data-maxlength');
+		}
+
+		input.removeAttribute('data-maxlength');
+		input.type = 'text';
+	} else if (input.origType) {
+		input.type = input.origType;
+		if (input.origMaxLength >= 0) {
+			input.setAttribute('data-maxlength', input.origMaxLength);
+		}
+	}
+
+	// Hide input value if it will be not used by selected function.
+	if (value === "NULL" || value === "now") {
+		if (input.value !== "") {
+			input.dataset.lastValue = input.value;
+			input.value = "";
+		}
+	} else if (input.dataset.lastValue) {
+		input.value = input.dataset.lastValue;
+	}
+
+	oninput({target: input});
+
 	helpClose();
 }
 
-/** Skip 'original' when typing
-* @param number
-* @this HTMLTableCellElement
-*/
+/**
+ * Unset 'original', 'NULL' and 'now' functions when typing.
+ *
+ * @param first number
+ * @this HTMLTableCellElement
+ */
 function skipOriginal(first) {
-	var fnSelect = this.previousSibling.firstChild;
-	if (fnSelect.selectedIndex < first) {
+	const fnSelect = this.previousSibling.firstChild;
+	const value = selectValue(fnSelect);
+
+	if (fnSelect.selectedIndex < first || value === "NULL" || value === "now") {
 		fnSelect.selectedIndex = first;
 	}
 }
diff --git a/editor/include/adminer.inc.php b/editor/include/adminer.inc.php
index 4d6d68f3..be9d7436 100644
--- a/editor/include/adminer.inc.php
+++ b/editor/include/adminer.inc.php
@@ -483,7 +483,7 @@ ORDER BY ORDINAL_POSITION", null, "") as $row) { //! requires MySQL 5
 		return $return;
 	}
 
-	function editInput($table, $field, $attrs, $value) {
+	function editInput($table, $field, $attrs, $value, $function) {
 		if ($field["type"] == "enum") {
 			return (isset($_GET["select"]) ? "<label><input type='radio'$attrs value='-1' checked><i>" . lang('original') . "</i></label> " : "")
 				. enum_input("radio", $attrs, $field, ($value || isset($_GET["select"]) ? $value : 0), ($field["null"] ? "" : null))
@@ -511,7 +511,9 @@ qsl('div').onclick = whisperClick;", "")
 			$hint = lang('[yyyy]-mm-dd') . ($hint ? " [$hint]" : "");
 		}
 		if ($hint) {
-			return "<input value='" . h($value) . "'$attrs> ($hint)"; //! maxlength
+			return "<input"
+				. ($function != "now" ? " value='" . h($value) . "'" : " data-last-value='" . h($value) . "'")
+				. "$attrs> ($hint)"; //! maxlength
 		}
 		if (preg_match('~_(md5|sha1)$~i', $field["field"])) {
 			return "<input type='password' value='" . h($value) . "'$attrs>";
diff --git a/plugins/plugin.php b/plugins/plugin.php
index 6defead8..ec7d9c04 100644
--- a/plugins/plugin.php
+++ b/plugins/plugin.php
@@ -335,7 +335,7 @@ class AdminerPlugin extends Adminer {
 		return $this->_applyPlugin(__FUNCTION__, $args);
 	}
 
-	function editInput($table, $field, $attrs, $value) {
+	function editInput($table, $field, $attrs, $value, $function) {
 		$args = func_get_args();
 		return $this->_applyPlugin(__FUNCTION__, $args);
 	}