diff --git a/src/components/QueryEditor.tsx b/src/components/QueryEditor.tsx
index 022889a..ef512b6 100644
--- a/src/components/QueryEditor.tsx
+++ b/src/components/QueryEditor.tsx
@@ -1,54 +1,141 @@
-import React, { useEffect, useState } from 'react';
+import React, { useEffect, useRef, useState } from 'react';
 import { QueryEditorProps, SelectableValue } from '@grafana/data';
-import { InlineField, Select, Input, Stack } from '@grafana/ui';
+import { Field, Select, AsyncSelect, Input, Button, stylesFactory } from '@grafana/ui';
 import { DataSource } from '../datasource';
-import { FhirDataSourceOptions, FhirQuery } from '../types';
+import { FhirDataSourceOptions, MyQuery, Filter } from '../types';
 
-type Props = QueryEditorProps<DataSource, FhirQuery, FhirDataSourceOptions>;
+function debouncePromise<F extends (...args: any[]) => Promise<any>>(fn: F, wait: number) {
+  let timer: NodeJS.Timeout | null = null;
+  let resolvers: Array<(value: any) => void> = [];
+  return ((...args: Parameters<F>): Promise<ReturnType<F>> => {
+    if (timer) {
+      clearTimeout(timer);
+    }
+    return new Promise<ReturnType<F>>((resolve) => {
+      resolvers.push(resolve);
+      timer = setTimeout(async () => {
+        const result = await fn(...args);
+        resolvers.forEach(r => r(result));
+        resolvers = [];
+      }, wait);
+    });
+  }) as F;
+}
+
+interface Props extends QueryEditorProps<DataSource, MyQuery, FhirDataSourceOptions> {}
+
+export function buildFhirSearchString(filters: Filter[]): string {
+  const opMap: Record<string, string> = { '!=': ':ne', '>': ':gt', '<': ':lt', contains: ':contains', '=': '' };
+  return filters
+    .filter(f => f.resourceType && f.field && f.value)
+    .map(f => `${f.resourceType}?${f.field}${opMap[f.operator || '='] || ''}=${f.value}`)
+    .join('&');
+}
+
+const operatorOptions: Array<SelectableValue<string>> = [
+  { label: '=', value: '=' },
+  { label: '!=', value: '!=' },
+  { label: '>', value: '>' },
+  { label: '<', value: '<' },
+  { label: 'contains', value: 'contains' },
+];
+
+const getStyles = stylesFactory(() => ({
+  row: {
+    display: 'flex',
+    alignItems: 'center',
+    gap: '8px',
+    marginBottom: '4px',
+  },
+}));
 
-export function QueryEditor({ query, datasource, onChange, onRunQuery }: Props) {
+export default function QueryEditor({ query, datasource, onChange, onRunQuery }: Props) {
+  const styles = getStyles();
   const [resources, setResources] = useState<Array<SelectableValue<string>>>([]);
-  const operatorOptions = [
-    { label: '==', value: '==' },
-    { label: '!=', value: '!=' },
-  ];
+  const fieldCache = useRef<Record<string, Array<SelectableValue<string>>>>({});
 
   useEffect(() => {
-    datasource.getResourceTypes().then((types) => setResources(types));
+    datasource.getResourceTypes().then(setResources);
   }, [datasource]);
 
-  const onResourceChange = (v: SelectableValue<string>) => {
-    onChange({ ...query, resourceType: v.value || '' });
-    onRunQuery();
+  useEffect(() => {
+    if (!query.filters || query.filters.length === 0) {
+      onChange({ ...query, filters: [{}] });
+    }
+  }, [query, onChange]);
+
+  const loadFields = async (rt: string) => {
+    if (fieldCache.current[rt]) {
+      return fieldCache.current[rt];
+    }
+    const opts = await datasource.getFields(rt);
+    fieldCache.current[rt] = opts;
+    return opts;
   };
 
-  const onParamChange = (v: React.ChangeEvent<HTMLInputElement>) => {
-    onChange({ ...query, searchParam: v.target.value });
+  const debouncedLoad = useRef(debouncePromise(loadFields, 300)).current;
+
+  const updateFilter = (idx: number, patch: Partial<Filter>) => {
+    const filters = query.filters.map((f, i) => (i === idx ? { ...f, ...patch } : f));
+    onChange({ ...query, filters });
+    onRunQuery();
   };
 
-  const onOperatorChange = (v: SelectableValue<string>) => {
-    onChange({ ...query, operator: v.value || '==' });
+  const addFilter = () => {
+    onChange({ ...query, filters: [...query.filters, {}] });
+    onRunQuery();
   };
 
-  const onValueChange = (v: React.ChangeEvent<HTMLInputElement>) => {
-    onChange({ ...query, searchValue: v.target.value });
+  const removeFilter = (idx: number) => {
+    const filters = query.filters.filter((_, i) => i !== idx);
+    onChange({ ...query, filters: filters.length > 0 ? filters : [{}] });
     onRunQuery();
   };
 
   return (
-    <Stack gap={1} wrap="nowrap" direction="row">
-      <InlineField label="Resource">
-        <Select options={resources} value={query.resourceType} onChange={onResourceChange} width={20} />
-      </InlineField>
-      <InlineField label="Search">
-        <Input width={20} value={query.searchParam || ''} onChange={onParamChange} placeholder="code" />
-      </InlineField>
-      <InlineField label="Op">
-        <Select options={operatorOptions} value={query.operator} onChange={onOperatorChange} width={8} />
-      </InlineField>
-      <InlineField label="Value">
-        <Input width={20} value={query.searchValue || ''} onChange={onValueChange} placeholder="*" />
-      </InlineField>
-    </Stack>
+    <div>
+      {query.filters.map((f, i) => (
+        <div className={styles.row} key={i}>
+          <Field label="Resource Type" horizontal>
+            <Select
+              options={resources}
+              value={f.resourceType}
+              onChange={v => updateFilter(i, { resourceType: v.value, field: undefined })}
+              width={20}
+            />
+          </Field>
+          <Field label="Field" horizontal>
+            <AsyncSelect
+              isDisabled={!f.resourceType}
+              loadOptions={(value) => (f.resourceType ? debouncedLoad(f.resourceType) : Promise.resolve([]))}
+              onChange={v => updateFilter(i, { field: v.value })}
+              value={f.field}
+              width={20}
+            />
+          </Field>
+          <Field label="Operator" horizontal>
+            <Select
+              options={operatorOptions}
+              value={f.operator}
+              onChange={v => updateFilter(i, { operator: v.value })}
+              isDisabled={!f.field}
+              width={12}
+            />
+          </Field>
+          <Field label="Value" horizontal>
+            <Input
+              value={f.value || ''}
+              onChange={e => updateFilter(i, { value: e.target.value }, true)}
+              disabled={!f.operator}
+              width={20}
+            />
+          </Field>
+          <Button variant="secondary" icon="trash-alt" onClick={() => removeFilter(i)} />
+        </div>
+      ))}
+      <Button variant="secondary" onClick={addFilter} icon="plus">
+        ＋ Add filter
+      </Button>
+    </div>
   );
 }
diff --git a/src/datasource.ts b/src/datasource.ts
index b71b2fc..21807b9 100644
--- a/src/datasource.ts
+++ b/src/datasource.ts
@@ -1,9 +1,9 @@
-import { DataSourceApi, DataSourceInstanceSettings, DataQueryRequest, DataQueryResponse, MutableDataFrame, FieldType } from '@grafana/data';
+import { DataSourceApi, DataSourceInstanceSettings, DataQueryRequest, DataQueryResponse, MutableDataFrame, FieldType, SelectableValue } from '@grafana/data';
 import { getBackendSrv } from '@grafana/runtime';
 import { firstValueFrom } from 'rxjs';
-import { FhirQuery, FhirDataSourceOptions, DEFAULT_QUERY } from './types';
+import { MyQuery, Filter, FhirDataSourceOptions, DEFAULT_QUERY } from './types';
 
-export class DataSource extends DataSourceApi<FhirQuery, FhirDataSourceOptions> {
+export class DataSource extends DataSourceApi<MyQuery, FhirDataSourceOptions> {
   instanceSettings: DataSourceInstanceSettings<FhirDataSourceOptions>;
 
   constructor(instanceSettings: DataSourceInstanceSettings<FhirDataSourceOptions>) {
@@ -29,29 +29,35 @@ export class DataSource extends DataSourceApi<FhirQuery, FhirDataSourceOptions>
     return DEFAULT_QUERY;
   }
 
-  async query(options: DataQueryRequest<FhirQuery>): Promise<DataQueryResponse> {
-    const promises = options.targets.map(t => this.fetchSeries(t));
+  async query(options: DataQueryRequest<MyQuery>): Promise<DataQueryResponse> {
+    const promises = options.targets.flatMap(target =>
+      target.filters.map(f => this.fetchSeries({ ...f, refId: target.refId }))
+    );
     const data = await Promise.all(promises);
     return { data };
   }
 
-  async fetchSeries(query: FhirQuery) {
+  async fetchSeries(filter: Filter & { refId?: string }) {
+    if (!filter.resourceType) {
+      return new MutableDataFrame({ refId: filter.refId, fields: [] });
+    }
     let params = '';
-    if (query.searchParam && query.searchValue) {
-      const prefix = query.operator === '!=' ? ':ne' : '';
-      params = `?${encodeURIComponent(query.searchParam)}${prefix}=${encodeURIComponent(query.searchValue)}`;
+    if (filter.field && filter.value) {
+      const opMap: Record<string, string> = { '!=': ':ne', '>': ':gt', '<': ':lt', contains: ':contains', '=': '' };
+      const op = opMap[filter.operator || '='] || '';
+      params = `?${encodeURIComponent(filter.field)}${op}=${encodeURIComponent(filter.value)}`;
     }
-    const url = `${this.getBaseUrl()}/${query.resourceType}${params}`;
+    const url = `${this.getBaseUrl()}/${filter.resourceType}${params}`;
     const res = await firstValueFrom(getBackendSrv().fetch<any>({ url }));
 
     const resources = (res.data.entry || []).map((e: any) => e.resource || {});
     if (resources.length === 0) {
-      return new MutableDataFrame({ refId: query.refId, fields: [] });
+      return new MutableDataFrame({ refId: filter.refId, fields: [] });
     }
 
     const columns: string[] = Array.from(new Set(resources.flatMap((r: any) => Object.keys(r)))) as string[];
     const fields = columns.map((name: string) => ({ name, type: FieldType.string }));
-    const frame = new MutableDataFrame({ refId: query.refId, fields });
+    const frame = new MutableDataFrame({ refId: filter.refId, fields });
 
     resources.forEach((r: any) => {
       const row: Record<string, any> = {};
@@ -93,4 +99,30 @@ export class DataSource extends DataSourceApi<FhirQuery, FhirDataSourceOptions>
       throw err;
     }
   }
+
+  async getFields(resourceType: string): Promise<Array<SelectableValue<string>>> {
+    const base = this.getBaseUrl();
+    try {
+      const res = await firstValueFrom(
+        getBackendSrv().fetch<any>({ url: `${base}/SearchParameter?base=${resourceType}` })
+      );
+      const entries = res.data.entry || [];
+      if (entries.length > 0) {
+        return entries.map((e: any) => ({ label: e.resource?.code, value: e.resource?.code }));
+      }
+    } catch (err) {
+      console.error('SearchParameter fetch failed', err);
+    }
+
+    try {
+      const res = await firstValueFrom(
+        getBackendSrv().fetch<any>({ url: `${base}/StructureDefinition/${resourceType}` })
+      );
+      const elements = res.data.snapshot?.element || [];
+      return elements.map((e: any) => ({ label: e.path, value: e.path }));
+    } catch (err) {
+      console.error('Failed to fetch fields', err);
+      return [];
+    }
+  }
 }
diff --git a/src/module.ts b/src/module.ts
index 84a9234..91e358d 100644
--- a/src/module.ts
+++ b/src/module.ts
@@ -1,9 +1,9 @@
 import { DataSourcePlugin } from '@grafana/data';
 import { DataSource } from './datasource';
 import { ConfigEditor } from './components/ConfigEditor';
-import { QueryEditor } from './components/QueryEditor';
-import { FhirQuery, FhirDataSourceOptions } from './types';
+import QueryEditor from './components/QueryEditor';
+import { MyQuery, FhirDataSourceOptions } from './types';
 
-export const plugin = new DataSourcePlugin<DataSource, FhirQuery, FhirDataSourceOptions>(DataSource)
+export const plugin = new DataSourcePlugin<DataSource, MyQuery, FhirDataSourceOptions>(DataSource)
   .setConfigEditor(ConfigEditor)
   .setQueryEditor(QueryEditor);
diff --git a/src/types.ts b/src/types.ts
index 345cb3f..c534041 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,15 +1,19 @@
 import { DataQuery, DataSourceJsonData } from '@grafana/data';
 
-export interface FhirQuery extends DataQuery {
-  resourceType: string;
-  searchParam?: string;
+export interface Filter {
+  resourceType?: string;
+  field?: string;
   operator?: string;
-  searchValue?: string;
+  value?: string;
 }
 
-export const DEFAULT_QUERY: Partial<FhirQuery> = {
-  resourceType: 'Observation',
-  operator: '==',
+export interface MyQuery extends DataQuery {
+  filters: Filter[];
+}
+
+export const DEFAULT_QUERY: MyQuery = {
+  refId: '',
+  filters: [{}],
 };
 
 export interface FhirDataSourceOptions extends DataSourceJsonData {