diff --git a/app/static/js/core/custom-functions-code.js b/app/static/js/core/custom-functions-code.js
index ea3aa9a..f1a844b 100644
--- a/app/static/js/core/custom-functions-code.js
+++ b/app/static/js/core/custom-functions-code.js
@@ -1,6 +1,261 @@
-async function hello(name) {
-  let r = await window.hello(name);
+// async function hello(name) {
+//   let r = await window.hello(name);
+//   return r.toJs();
+// }
+
+// CustomFunctions.associate("HELLO", hello);
+
+// async function sql(query, tables) {
+//   let r = await window.sql(query, tables);
+//   return r.toJs();
+// }
+
+// CustomFunctions.associate("SQL", sql);
+
+/////////////////////////////////////////
+
+const debug = false;
+let invocations = new Set();
+let bodies = new Set();
+let runtime;
+let contentLanguage;
+let socket = null;
+
+Office.onReady(function (info) {
+  // Socket.io
+  socket = globalThis.socket ? globalThis.socket : null;
+
+  if (socket !== null) {
+    socket.on("disconnect", () => {
+      if (debug) {
+        console.log("disconnect");
+      }
+      for (let invocation of invocations) {
+        invocation.setResult([["Stream disconnected"]]);
+      }
+      invocations.clear();
+    });
+
+    socket.on("connect", () => {
+      // Without this, you'd have to hit Ctrl+Alt+F9, which isn't available on the web
+      if (debug) {
+        console.log("connect");
+      }
+      for (let body of bodies) {
+        socket.emit("xlwings:function-call", body);
+      }
+    });
+  }
+
+  // Runtime version
+  if (
+    Office.context.requirements.isSetSupported("CustomFunctionsRuntime", "1.4")
+  ) {
+    runtime = "1.4";
+  } else if (
+    Office.context.requirements.isSetSupported("CustomFunctionsRuntime", "1.3")
+  ) {
+    runtime = "1.3";
+  } else if (
+    Office.context.requirements.isSetSupported("CustomFunctionsRuntime", "1.2")
+  ) {
+    runtime = "1.2";
+  } else {
+    runtime = "1.1";
+  }
+
+  // Content Language
+  contentLanguage = Office.context.contentLanguage;
+});
+
+function flattenVarargsArray(arr) {
+  // Turn [ [[0]], [ [[0]], [[0]] ] ] into:
+  // result: [ [[0]], [[0]], [[0]] ]
+  // indices: [ [ 0 ], [ 1, 0 ], [ 1, 1 ] ]
+  const result = [];
+  const indices = [];
+
+  function isTripleNested(item) {
+    return (
+      Array.isArray(item) && Array.isArray(item[0]) && Array.isArray(item[0][0])
+    );
+  }
+
+  for (let i = 0; i < arr.length; i++) {
+    const item = arr[i];
+
+    if (isTripleNested(item)) {
+      result.push(...item);
+      for (let j = 0; j < item.length; j++) {
+        indices.push([i, j]);
+      }
+    } else {
+      result.push(item);
+      indices.push([i]);
+    }
+  }
+
+  return {
+    result,
+    indices,
+  };
+}
+
+// Workbook name
+let cachedWorkbookName = null;
+
+async function getWorkbookName() {
+  if (cachedWorkbookName) {
+    return cachedWorkbookName;
+  }
+  const context = new Excel.RequestContext();
+  const workbook = context.workbook;
+  workbook.load("name");
+  await context.sync();
+  cachedWorkbookName = workbook.name;
+  return cachedWorkbookName;
+}
+
+class Semaphore {
+  constructor(maxConcurrency) {
+    this.maxConcurrency = maxConcurrency;
+    this.currentConcurrency = 0;
+    this.queue = [];
+  }
+
+  async acquire() {
+    if (this.currentConcurrency < this.maxConcurrency) {
+      this.currentConcurrency++;
+      return;
+    }
+    return new Promise((resolve) => this.queue.push(resolve));
+  }
+
+  release() {
+    this.currentConcurrency--;
+    if (this.queue.length > 0) {
+      this.currentConcurrency++;
+      const nextResolve = this.queue.shift();
+      nextResolve();
+    }
+  }
+}
+
+const semaphore = new Semaphore(1000);
+
+async function base() {
+  await Office.onReady(); // Block execution until office.js is ready
+  // Arguments
+  let argsArr = Array.prototype.slice.call(arguments);
+  let funcName = argsArr[0];
+  let isStreaming = argsArr[1];
+  let args = argsArr.slice(2, -1);
+  let invocation = argsArr[argsArr.length - 1];
+
+  const workbookName = await getWorkbookName();
+  const officeApiClient = localStorage.getItem("Office API client");
+
+  // For arguments that are Entities, replace the arg with their address (cache key).
+  // The issues is that invocation.parameterAddresses returns a flat list while args
+  // contains a nested array for varargs (in Office.js called 'repeating').
+  const { result: flatArgs, indices } = flattenVarargsArray(args);
+
+  // Process each flattened item with respect to its path
+  flatArgs.forEach((item, index) => {
+    if (item && item[0][0]?.type === "Entity") {
+      const address = `${officeApiClient}[${workbookName}]${invocation.parameterAddresses[index]}`;
+
+      let target = args;
+      const path = indices[index];
+
+      for (let i = 0; i < path.length - 1; i++) {
+        target = target[path[i]];
+      }
+
+      const lastIndex = path[path.length - 1];
+      target[lastIndex] = [address];
+    }
+  });
+
+  // Body
+  let body = {
+    func_name: funcName,
+    args: args,
+    caller_address: `${officeApiClient}[${workbookName}]${invocation.address}`, // not available for streaming functions
+    content_language: contentLanguage,
+    version: "0.33.3",
+    runtime: runtime,
+  };
+
+  // Streaming functions communicate via socket.io
+  if (isStreaming) {
+    if (socket === null) {
+      console.error(
+        "To enable streaming functions, you need to load the socket.io js client before xlwings.min.js and custom-functions-code",
+      );
+      return;
+    }
+    let taskKey = `${funcName}_${args}`;
+    body.task_key = taskKey;
+    socket.emit("xlwings:function-call", body);
+    if (debug) {
+      console.log(`emit xlwings:function-call ${funcName}`);
+    }
+    invocation.setResult([["Waiting for stream..."]]);
+
+    socket.off(`xlwings:set-result-${taskKey}`);
+    socket.on(`xlwings:set-result-${taskKey}`, (data) => {
+      invocation.setResult(data.result);
+      if (debug) {
+        console.log(`Set Result`);
+      }
+    });
+
+    invocations.add(invocation);
+    bodies.add(body);
+
+    return;
+  }
+
+  // Normal functions communicate via REST API
+  return await makeJsCall(body);
+}
+
+async function makeJsCall(body) {
+  const processedArgs = body.args
+    ? body.args.map((arg) => JSON.stringify(arg))
+    : [];
+
+  // Call function with processed arguments
+  let r = await window[body.func_name](...processedArgs);
   return r.toJs();
 }
 
+function showError(errorMessage) {
+  if (
+    Office.context.requirements.isSetSupported("CustomFunctionsRuntime", "1.2")
+  ) {
+    // Error message is only visible by hovering over the error flag!
+    let excelError = new CustomFunctions.Error(
+      CustomFunctions.ErrorCode.invalidValue,
+      errorMessage,
+    );
+    throw excelError;
+  } else {
+    return [[errorMessage]];
+  }
+}
+
+async function hello() {
+  let args = ["hello", false];
+  args.push.apply(args, arguments);
+  return await base.apply(null, args);
+}
 CustomFunctions.associate("HELLO", hello);
+
+async function sql() {
+  let args = ["sql", false];
+  args.push.apply(args, arguments);
+  return await base.apply(null, args);
+}
+CustomFunctions.associate("SQL", sql);
diff --git a/app/static/main.py b/app/static/main.py
index 6bb1c96..0909f2b 100644
--- a/app/static/main.py
+++ b/app/static/main.py
@@ -7,11 +7,12 @@
 
 import json
 import os
+import sqlite3
 
-import matplotlib as mpl
-import matplotlib.pyplot as plt
-
-mpl.use("agg")
+# To use matplotlib, add it to pyscript.json
+# import matplotlib as mpl
+# import matplotlib.pyplot as plt
+# mpl.use("agg")
 
 os.environ["XLWINGS_LICENSE_KEY"] = "noncommercial"
 import xlwings as xw  # noqa: E402
@@ -31,10 +32,10 @@ async def test(event):
     print(sheet1["A1:A2"].value)
     book.sheets[0]["A3"].value = "xxxxxxx"
 
-    fig = plt.figure()
-    plt.plot([1, 2, 3])
-    sheet1.pictures.add(fig, name="MyPlot", update=True, anchor=sheet1["C5"])
-    sheet1["A1"].select()
+    # fig = plt.figure()
+    # plt.plot([1, 2, 3])
+    # sheet1.pictures.add(fig, name="MyPlot", update=True, anchor=sheet1["C5"])
+    # sheet1["A1"].select()
 
     # Process actions (this could be improved so methods are applied immediately)
     xwjs.runActionsStandalone(json.dumps(book.json()))
@@ -46,3 +47,84 @@ async def hello(name):
 
 
 window.hello = hello
+
+
+# @func
+# @arg("tables", expand="table", ndim=2)
+async def sql(query, *tables):
+    print("xx", query)
+    query = json.loads(query)[0][0]
+    print("yy", tables)
+    processed_tables = [
+        json.loads(table) if isinstance(table, str) else table
+        for table in tables  # TODO: remove ending [0] when converter applied
+    ]
+    print("zz", processed_tables)
+    res = _sql(query, *processed_tables)
+    print("rr", res)
+    return res
+
+
+window.sql = sql
+
+
+def conv_value(value, col_is_str):
+    if value is None:
+        return "NULL"
+    if col_is_str:
+        return repr(str(value))
+    elif isinstance(value, bool):
+        return 1 if value else 0
+    else:
+        return repr(value)
+
+
+def _sql(query, *tables):
+    conn = sqlite3.connect(":memory:")
+    print("t", tables)
+
+    c = conn.cursor()
+    for i, table in enumerate(tables):
+        # TODO: remove [0] in next 2 rows
+        cols = table[0][0]
+        rows = table[0][1:]
+        print(cols)
+        print(rows)
+        types = [any(isinstance(row[j], str) for row in rows) for j in range(len(cols))]
+        name = chr(65 + i)
+
+        stmt = "CREATE TABLE %s (%s)" % (
+            name,
+            ", ".join(
+                "'%s' %s" % (col, "STRING" if typ else "REAL")
+                for col, typ in zip(cols, types)
+            ),
+        )
+        c.execute(stmt)
+
+        if rows:
+            stmt = "INSERT INTO %s VALUES %s" % (
+                name,
+                ", ".join(
+                    "(%s)"
+                    % ", ".join(
+                        conv_value(value, type) for value, typ in zip(row, types)
+                    )
+                    for row in rows
+                ),
+            )
+            # Fixes values like these:
+            # sql('SELECT a FROM a', [['a', 'b'], ["""X"Y'Z""", 'd']])
+            stmt = stmt.replace("\\'", "''")
+            c.execute(stmt)
+
+    res = []
+    c.execute(query)
+    res.append([x[0] for x in c.description])
+    for row in c:
+        res.append(list(row))
+    print("marker3")
+    print(res)
+    print(type(res))
+
+    return res
diff --git a/app/static/pyscript.json b/app/static/pyscript.json
index 327ecc2..a70aeb0 100644
--- a/app/static/pyscript.json
+++ b/app/static/pyscript.json
@@ -1,3 +1,3 @@
 {
-  "packages": ["xlwings", "matplotlib"]
+  "packages": ["xlwings", "sqlite3"]
 }