feat: Support limiting row count and offsets in Oracle queries (#754)

Author: danielenricocahall

pypika/dialects.py

@@ -1,4 +1,5 @@
 import itertools
+import warnings
 from copy import copy
 from typing import Any, Optional, Union, Tuple as TypedTuple
 
@@ -347,6 +348,19 @@ def __str__(self) -> str:
         return self.get_sql()
 
 
+class FetchNextAndOffsetRowsQueryBuilder(QueryBuilder):
+    def _limit_sql(self) -> str:
+        return " FETCH NEXT {limit} ROWS ONLY".format(limit=self._limit)
+
+    def _offset_sql(self) -> str:
+        return " OFFSET {offset} ROWS".format(offset=self._offset or 0)
+
+    @builder
+    def fetch_next(self, limit: int):
+        warnings.warn("`fetch_next` is deprecated - please use the `limit` method", DeprecationWarning)
+        self._limit = limit
+
+
 class OracleQuery(Query):
     """
     Defines a query class for use with Oracle.
@@ -357,7 +371,7 @@ def _builder(cls, **kwargs: Any) -> "OracleQueryBuilder":
         return OracleQueryBuilder(**kwargs)
 
 
-class OracleQueryBuilder(QueryBuilder):
+class OracleQueryBuilder(FetchNextAndOffsetRowsQueryBuilder):
     QUOTE_CHAR = None
     QUERY_CLS = OracleQuery
 
@@ -370,6 +384,16 @@ def get_sql(self, *args: Any, **kwargs: Any) -> str:
         kwargs['groupby_alias'] = False
         return super().get_sql(*args, **kwargs)
 
+    def _apply_pagination(self, querystring: str) -> str:
+        # Note: Overridden as Oracle specifies offset before the fetch next limit
+        if self._offset:
+            querystring += self._offset_sql()
+
+        if self._limit is not None:
+            querystring += self._limit_sql()
+
+        return querystring
+
 
 class PostgreSQLQuery(Query):
     """
@@ -670,7 +694,7 @@ def _builder(cls, **kwargs: Any) -> "MSSQLQueryBuilder":
         return MSSQLQueryBuilder(**kwargs)
 
 
-class MSSQLQueryBuilder(QueryBuilder):
+class MSSQLQueryBuilder(FetchNextAndOffsetRowsQueryBuilder):
     QUERY_CLS = MSSQLQuery
 
     def __init__(self, **kwargs: Any) -> None:
@@ -695,17 +719,6 @@ def top(self, value: Union[str, int], percent: bool = False, with_ties: bool = F
         self._top_percent: bool = percent
         self._top_with_ties: bool = with_ties
 
-    @builder
-    def fetch_next(self, limit: int) -> "MSSQLQueryBuilder":
-        # Overridden to provide a more domain-specific API for T-SQL users
-        self._limit = limit
-
-    def _offset_sql(self) -> str:
-        return " OFFSET {offset} ROWS".format(offset=self._offset or 0)
-
-    def _limit_sql(self) -> str:
-        return " FETCH NEXT {limit} ROWS ONLY".format(limit=self._limit)
-
     def _apply_pagination(self, querystring: str) -> str:
         # Note: Overridden as MSSQL specifies offset before the fetch next limit
         if self._limit is not None or self._offset:

pypika/tests/dialects/test_mssql.py

@@ -53,18 +53,13 @@ def test_limit(self):
 
         self.assertEqual('SELECT "def" FROM "abc" ORDER BY "def" OFFSET 0 ROWS FETCH NEXT 10 ROWS ONLY', str(q))
 
-    def test_fetch_next(self):
-        q = MSSQLQuery.from_("abc").select("def").orderby("def").fetch_next(10)
-
-        self.assertEqual('SELECT "def" FROM "abc" ORDER BY "def" OFFSET 0 ROWS FETCH NEXT 10 ROWS ONLY', str(q))
-
     def test_offset(self):
         q = MSSQLQuery.from_("abc").select("def").orderby("def").offset(10)
 
         self.assertEqual('SELECT "def" FROM "abc" ORDER BY "def" OFFSET 10 ROWS', str(q))
 
-    def test_fetch_next_with_offset(self):
-        q = MSSQLQuery.from_("abc").select("def").orderby("def").fetch_next(10).offset(10)
+    def test_limit_with_offset(self):
+        q = MSSQLQuery.from_("abc").select("def").orderby("def").limit(10).offset(10)
 
         self.assertEqual('SELECT "def" FROM "abc" ORDER BY "def" OFFSET 10 ROWS FETCH NEXT 10 ROWS ONLY', str(q))
 

pypika/tests/dialects/test_oracle.py

@@ -19,3 +19,33 @@ def test_groupby_alias_False_does_not_group_by_alias_when_subqueries_are_present
         q = OracleQuery.from_(subquery).select(col, Count('*')).groupby(col)
 
         self.assertEqual('SELECT sq0.abc a,COUNT(\'*\') FROM (SELECT abc FROM table1) sq0 GROUP BY sq0.abc', str(q))
+
+    def test_limit_query(self):
+        t = Table('table1')
+        limit = 5
+        q = OracleQuery.from_(t).select(t.test).limit(limit)
+
+        self.assertEqual(f'SELECT test FROM table1 FETCH NEXT {limit} ROWS ONLY', str(q))
+
+    def test_offset_query(self):
+        t = Table('table1')
+        offset = 5
+        q = OracleQuery.from_(t).select(t.test).offset(offset)
+
+        self.assertEqual(f'SELECT test FROM table1 OFFSET {offset} ROWS', str(q))
+
+    def test_limit_offset_query(self):
+        t = Table('table1')
+        limit = 5
+        offset = 5
+        q = OracleQuery.from_(t).select(t.test).limit(limit).offset(offset)
+
+        self.assertEqual(f'SELECT test FROM table1 OFFSET {offset} ROWS FETCH NEXT {limit} ROWS ONLY', str(q))
+
+    def test_fetch_next_method_deprecated(self):
+        with self.assertWarns(DeprecationWarning):
+            t = Table('table1')
+            limit = 5
+            q = OracleQuery.from_(t).select(t.test).fetch_next(limit)
+
+            self.assertEqual(f'SELECT test FROM table1 FETCH NEXT {limit} ROWS ONLY', str(q))