1 files changed, 42 insertions, 1 deletions
diff --git a/sqlglot/executor/table.py b/sqlglot/executor/table.py
index 6796740..f1b5b54 100644
--- a/sqlglot/executor/table.py
+++ b/sqlglot/executor/table.py
@@ -1,14 +1,27 @@
+from __future__ import annotations
+
+from sqlglot.helper import dict_depth
+from sqlglot.schema import AbstractMappingSchema
+
+
 class Table:
     def __init__(self, columns, rows=None, column_range=None):
         self.columns = tuple(columns)
         self.column_range = column_range
         self.reader = RowReader(self.columns, self.column_range)
-
         self.rows = rows or []
         if rows:
             assert len(rows[0]) == len(self.columns)
         self.range_reader = RangeReader(self)
 
+    def add_columns(self, *columns: str) -> None:
+        self.columns += columns
+        if self.column_range:
+            self.column_range = range(
+                self.column_range.start, self.column_range.stop + len(columns)
+            )
+        self.reader = RowReader(self.columns, self.column_range)
+
     def append(self, row):
         assert len(row) == len(self.columns)
         self.rows.append(row)
@@ -87,3 +100,31 @@ class RowReader:
 
     def __getitem__(self, column):
         return self.row[self.columns[column]]
+
+
+class Tables(AbstractMappingSchema[Table]):
+    pass
+
+
+def ensure_tables(d: dict | None) -> Tables:
+    return Tables(_ensure_tables(d))
+
+
+def _ensure_tables(d: dict | None) -> dict:
+    if not d:
+        return {}
+
+    depth = dict_depth(d)
+
+    if depth > 1:
+        return {k: _ensure_tables(v) for k, v in d.items()}
+
+    result = {}
+    for name, table in d.items():
+        if isinstance(table, Table):
+            result[name] = table
+        else:
+            columns = tuple(table[0]) if table else ()
+            rows = [tuple(row[c] for c in columns) for row in table]
+            result[name] = Table(columns=columns, rows=rows)
+    return result