From 169ea455fc1f1d5e5b6e44cb339ba7ffa9d49c31 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Mon, 4 Nov 2019 08:18:06 -0800
Subject: [PATCH] Added table.delete_where(), closes #62

---
 docs/python-api.rst  | 11 +++++++++++
 sqlite_utils/db.py   |  8 ++++++++
 tests/test_delete.py | 18 ++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/docs/python-api.rst b/docs/python-api.rst
index 374bdc6..cadad15 100644
--- a/docs/python-api.rst
+++ b/docs/python-api.rst
@@ -396,6 +396,17 @@ The ``delete()`` method takes the primary key of the record. This can be a tuple
 
     >>> db["compound_dogs"].delete((5, 3))
 
+Deleting multiple records
+=========================
+
+You can delete all records in a table that match a specific WHERE statement using ``table.delete_where()``::
+
+    >>> db = sqlite_utils.Database("dogs.db")
+    >>> # Delete every dog with age less than 3
+    >>> db["dogs"].delete_where("age < ?", [3]):
+
+Calling ``table.delete_where()`` with no other arguments will delete every row in the table.
+
 Upserting data
 ==============
 
diff --git a/sqlite_utils/db.py b/sqlite_utils/db.py
index 68a2002..a51bba7 100644
--- a/sqlite_utils/db.py
+++ b/sqlite_utils/db.py
@@ -864,6 +864,14 @@ class Table(Queryable):
         with self.db.conn:
             self.db.conn.execute(sql, pk_values)
 
+    def delete_where(self, where=None, where_args=None):
+        if not self.exists:
+            return []
+        sql = "delete from [{}]".format(self.name)
+        if where is not None:
+            sql += " where " + where
+        self.db.conn.execute(sql, where_args or [])
+
     def update(self, pk_values, updates=None, alter=False):
         updates = updates or {}
         if not isinstance(pk_values, (list, tuple)):
diff --git a/tests/test_delete.py b/tests/test_delete.py
index 6758831..1198d06 100644
--- a/tests/test_delete.py
+++ b/tests/test_delete.py
@@ -12,3 +12,21 @@ def test_delete_pk_table(fresh_db):
     table.insert({"id": 2}, pk="id")
     table.delete(1)
     assert [{"id": 2}] == list(table.rows)
+
+
+def test_delete_where(fresh_db):
+    table = fresh_db["table"]
+    for i in range(1, 11):
+        table.insert({"id": i}, pk="id")
+    assert 10 == table.count
+    table.delete_where("id > ?", [5])
+    assert 5 == table.count
+
+
+def test_delete_where_all(fresh_db):
+    table = fresh_db["table"]
+    for i in range(1, 11):
+        table.insert({"id": i}, pk="id")
+    assert 10 == table.count
+    table.delete_where()
+    assert 0 == table.count