diff --git a/dao/src/main/java/org/thingsboard/server/dao/sql/query/EntityKeyMapping.java b/dao/src/main/java/org/thingsboard/server/dao/sql/query/EntityKeyMapping.java
index 313a44f4a3..9ed515f518 100644
--- a/dao/src/main/java/org/thingsboard/server/dao/sql/query/EntityKeyMapping.java
+++ b/dao/src/main/java/org/thingsboard/server/dao/sql/query/EntityKeyMapping.java
@@ -519,6 +519,9 @@ public class EntityKeyMapping {
         String operationField = field;
         String paramName = getNextParameterName(field);
         String value = stringFilterPredicate.getValue().getValue();
+        if (value.isEmpty()) {
+            return null;
+        }
         String stringOperationQuery = "";
         if (stringFilterPredicate.isIgnoreCase()) {
             value = value.toLowerCase();
@@ -526,30 +529,26 @@ public class EntityKeyMapping {
         }
         switch (stringFilterPredicate.getOperation()) {
             case EQUAL:
-                stringOperationQuery = String.format("%s = :%s) or (%s is null and :%s = '')", operationField, paramName, operationField, paramName);
+                stringOperationQuery = String.format("%s = :%s)", operationField, paramName);
                 break;
             case NOT_EQUAL:
-                stringOperationQuery = String.format("%s != :%s) or (%s is null and :%s != '')", operationField, paramName, operationField, paramName);
+                stringOperationQuery = String.format("%s != :%s or %s is null)", operationField, paramName, operationField);
                 break;
             case STARTS_WITH:
                 value += "%";
-                stringOperationQuery = String.format("%s like :%s) or (%s is null and :%s = '%%')", operationField, paramName, operationField, paramName);
+                stringOperationQuery = String.format("%s like :%s)", operationField, paramName);
                 break;
             case ENDS_WITH:
                 value = "%" + value;
-                stringOperationQuery = String.format("%s like :%s) or (%s is null and :%s = '%%')", operationField, paramName, operationField, paramName);
+                stringOperationQuery = String.format("%s like :%s)", operationField, paramName);
                 break;
             case CONTAINS:
-                if (value.length() > 0) {
-                    value = "%" + value + "%";
-                }
-                stringOperationQuery = String.format("%s like :%s) or (%s is null and :%s = '')", operationField, paramName, operationField, paramName);
+                value = "%" + value + "%";
+                stringOperationQuery = String.format("%s like :%s)", operationField, paramName);
                 break;
             case NOT_CONTAINS:
-                if (value.length() > 0) {
-                    value = "%" + value + "%";
-                }
-                stringOperationQuery = String.format("%s not like :%s) or (%s is null and :%s != '')", operationField, paramName, operationField, paramName);
+                value = "%" + value + "%";
+                stringOperationQuery = String.format("%s not like :%s or %s is null)", operationField, paramName, operationField);
                 break;
         }
         ctx.addStringParameter(paramName, value);
diff --git a/dao/src/test/java/org/thingsboard/server/dao/service/BaseEntityServiceTest.java b/dao/src/test/java/org/thingsboard/server/dao/service/BaseEntityServiceTest.java
index 6c899c01c4..6b7530c4c3 100644
--- a/dao/src/test/java/org/thingsboard/server/dao/service/BaseEntityServiceTest.java
+++ b/dao/src/test/java/org/thingsboard/server/dao/service/BaseEntityServiceTest.java
@@ -17,6 +17,7 @@ package org.thingsboard.server.dao.service;
 
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
+import org.apache.commons.lang3.RandomUtils;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -56,6 +57,7 @@ import org.thingsboard.server.common.data.query.KeyFilter;
 import org.thingsboard.server.common.data.query.NumericFilterPredicate;
 import org.thingsboard.server.common.data.query.RelationsQueryFilter;
 import org.thingsboard.server.common.data.query.StringFilterPredicate;
+import org.thingsboard.server.common.data.query.StringFilterPredicate.StringOperation;
 import org.thingsboard.server.common.data.relation.EntityRelation;
 import org.thingsboard.server.common.data.relation.EntitySearchDirection;
 import org.thingsboard.server.common.data.relation.RelationEntityTypeFilter;
@@ -72,6 +74,9 @@ import java.util.List;
 import java.util.Random;
 import java.util.concurrent.ExecutionException;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
 
 public abstract class BaseEntityServiceTest extends AbstractServiceTest {
 
@@ -541,6 +546,155 @@ public abstract class BaseEntityServiceTest extends AbstractServiceTest {
         deviceService.deleteDevicesByTenantId(tenantId);
     }
 
+    @Test
+    public void testFindEntityDataByQuery_operationEqual_emptySearchQuery() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.EQUAL, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size(), result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationNotEqual() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = devices.get(2).getLabel();
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.NOT_EQUAL, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size() - 1, result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationNotEqual_emptySearchQuery() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.NOT_EQUAL, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size(), result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationStartsWith_emptySearchQuery() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.STARTS_WITH, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size(), result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationEndsWith_emptySearchQuery() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.ENDS_WITH, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size(), result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationContains_emptySearchQuery() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.CONTAINS, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size(), result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationNotContains() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "label-";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.NOT_CONTAINS, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(2, result.getTotalElements());
+    }
+
+    @Test
+    public void testFindEntityDataByQuery_operationNotContains_emptySearchQuery() {
+        List<Device> devices = createMockDevices(10);
+        devices.get(0).setLabel("");
+        devices.get(1).setLabel(null);
+        devices.forEach(deviceService::saveDevice);
+
+        String searchQuery = "";
+        EntityDataQuery query = createDeviceSearchQuery("label", StringOperation.NOT_CONTAINS, searchQuery);
+
+        PageData<EntityData> result = searchEntities(query);
+        assertEquals(devices.size(), result.getTotalElements());
+    }
+
+    private PageData<EntityData> searchEntities(EntityDataQuery query) {
+        return entityService.findEntityDataByQuery(tenantId, new CustomerId(CustomerId.NULL_UUID), query);
+    }
+
+    private EntityDataQuery createDeviceSearchQuery(String deviceField, StringOperation operation, String searchQuery) {
+        DeviceTypeFilter deviceTypeFilter = new DeviceTypeFilter();
+        deviceTypeFilter.setDeviceType("default");
+        deviceTypeFilter.setDeviceNameFilter("");
+
+        EntityDataSortOrder sortOrder = new EntityDataSortOrder(
+                new EntityKey(EntityKeyType.ENTITY_FIELD, "createdTime"), EntityDataSortOrder.Direction.ASC
+        );
+        EntityDataPageLink pageLink = new EntityDataPageLink(1000, 0, null, sortOrder);
+        List<EntityKey> entityFields = Arrays.asList(
+                new EntityKey(EntityKeyType.ENTITY_FIELD, "name"),
+                new EntityKey(EntityKeyType.ENTITY_FIELD, "label")
+        );
+
+        List<KeyFilter> keyFilters = createStringKeyFilters(deviceField, EntityKeyType.ENTITY_FIELD, operation, searchQuery);
+
+        return new EntityDataQuery(deviceTypeFilter, pageLink, entityFields, null, keyFilters);
+    }
+
+    private List<Device> createMockDevices(int count) {
+        return Stream.iterate(1, i -> i + 1)
+                .map(i -> {
+                    Device device = new Device();
+                    device.setTenantId(tenantId);
+                    device.setName("Device " + i);
+                    device.setType("default");
+                    device.setLabel("label-" + RandomUtils.nextInt(100, 10000));
+                    return device;
+                })
+                .limit(count)
+                .collect(Collectors.toList());
+    }
+
     @Test
     public void testFindEntityDataByQueryWithAttributes() throws ExecutionException, InterruptedException {