From 4128c4b0186a7f0e1051733a02fbf443d0d86927 Mon Sep 17 00:00:00 2001
From: David Wobrock <david.wobrock@gmail.com>
Date: Mon, 29 Jul 2019 21:14:05 +0200
Subject: [PATCH] Add logic to detect DROP TABLE

---
 django_migration_linter/sql_analyser/base.py   |  6 ++++++
 django_migration_linter/sql_analyser/sqlite.py | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/django_migration_linter/sql_analyser/base.py b/django_migration_linter/sql_analyser/base.py
index ade1ef8..20fa325 100644
--- a/django_migration_linter/sql_analyser/base.py
+++ b/django_migration_linter/sql_analyser/base.py
@@ -49,6 +49,12 @@ class BaseAnalyser(object):
             "err_msg": "DROPPING columns",
             "mode": "one_liner",
         },
+        {
+            "code": "DROP_TABLE",
+            "fn": lambda sql, **kw: sql.startswith("DROP TABLE"),
+            "err_msg": "DROPPING table",
+            "mode": "one_liner",
+        },
         {
             "code": "RENAME_COLUMN",
             "fn": lambda sql, **kw: re.search("ALTER TABLE .* CHANGE", sql)
diff --git a/django_migration_linter/sql_analyser/sqlite.py b/django_migration_linter/sql_analyser/sqlite.py
index 49b09e2..e4d8a91 100644
--- a/django_migration_linter/sql_analyser/sqlite.py
+++ b/django_migration_linter/sql_analyser/sqlite.py
@@ -25,6 +25,16 @@ class SqliteAnalyser(BaseAnalyser):
             and "__old" not in sql
             and "new__" not in sql,
         },
+        {
+            "code": "DROP_TABLE",
+            # TODO: improve to detect that the table names overlap
+            "fn": lambda sql_statements, **kw: any(
+                sql.startswith("DROP TABLE") for sql in sql_statements
+            )
+            and not any(sql.startswith("CREATE TABLE") for sql in sql_statements),
+            "err_msg": "DROPPING table",
+            "mode": "transaction",
+        },
         {
             "code": "NOT_NULL",
             "fn": lambda sql_statements, **kw: any(