Intermediate changes

commit_hash:2a2a4a29a447b6b9c8f7d148b02f33aa5942f64e

1 files changed, 74 insertions, 0 deletions

diff --git a/contrib/python/clickhouse-connect/clickhouse_connect/cc_sqlalchemy/sql/compiler.py b/contrib/python/clickhouse-connect/clickhouse_connect/cc_sqlalchemy/sql/compiler.py
new file mode 100644
index 00000000000..dab2099ef24
--- /dev/null
+++ b/contrib/python/clickhouse-connect/clickhouse_connect/cc_sqlalchemy/sql/compiler.py
@@ -0,0 +1,74 @@
+from sqlalchemy.exc import CompileError
+from sqlalchemy.sql.compiler import SQLCompiler
+
+from clickhouse_connect.cc_sqlalchemy.sql import format_table
+
+
+# pylint: disable=arguments-differ
+class ChStatementCompiler(SQLCompiler):
+
+    # pylint: disable=attribute-defined-outside-init
+    def visit_delete(self, delete_stmt, visiting_cte=None, **kw):
+        table = delete_stmt.table
+        text = f"DELETE FROM {format_table(table)}"
+
+        if delete_stmt.whereclause is not None:
+            self._in_delete_where = True
+            try:
+                text += " WHERE " + self.process(delete_stmt.whereclause, **kw)
+            finally:
+                self._in_delete_where = False
+        else:
+            raise CompileError("ClickHouse DELETE statements require a WHERE clause. To delete all rows, use 'TRUNCATE TABLE' instead.")
+
+        return text
+
+    def visit_select(self, select_stmt, **kw):
+        return super().visit_select(select_stmt, **kw)
+
+    def visit_join(self, join, **kw):
+        left = self.process(join.left, **kw)
+        right = self.process(join.right, **kw)
+        onclause = join.onclause
+
+        if getattr(join, "full", False):
+            join_kw = " FULL OUTER JOIN "
+        elif onclause is None:
+            join_kw = " CROSS JOIN "
+        elif join.isouter:
+            join_kw = " LEFT OUTER JOIN "
+        else:
+            join_kw = " INNER JOIN "
+
+        text = left + join_kw + right
+
+        if onclause is not None:
+            text += " ON " + self.process(onclause, **kw)
+
+        return text
+
+    def visit_column(self, column, add_to_result_map=None, include_table=True, result_map_targets=(), ambiguous_table_name_map=None, **kw):
+        if getattr(self, "_in_delete_where", False):
+            return self.preparer.quote(column.name)
+
+        return super().visit_column(
+            column,
+            add_to_result_map=add_to_result_map,
+            include_table=include_table,
+            result_map_targets=result_map_targets,
+            **kw,
+        )
+
+    # Abstract methods required by SQLCompiler
+    def delete_extra_from_clause(self, delete_stmt, from_table, extra_froms, from_hints, **kw):
+        raise NotImplementedError("ClickHouse doesn't support DELETE with extra FROM clause")
+
+    def update_from_clause(self, update_stmt, from_table, extra_froms, from_hints, **kw):
+        raise NotImplementedError("ClickHouse doesn't support UPDATE with FROM clause")
+
+    # pylint: disable=unused-argument
+    def visit_empty_set_expr(self, element_types, **kw):
+        return "SELECT 1 WHERE 1=0"
+
+    def visit_sequence(self, sequence, **kw):
+        raise NotImplementedError("ClickHouse doesn't support sequences")