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-rw-r--r--lib/sqlalchemy/sql/elements.py30
1 files changed, 30 insertions, 0 deletions
diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index 58db56a9c..04565443d 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -3272,6 +3272,36 @@ class Extract(ColumnElement):
as well as ``func.extract`` from the
:data:`.func` namespace.
+ :param field: The field to extract.
+
+ :param expr: A column or Python scalar expression serving as the
+ right side of the ``EXTRACT`` expression.
+
+ E.g.::
+
+ from sqlalchemy import extract
+ from sqlalchemy import table, column
+
+ logged_table = table("user",
+ column("id"),
+ column("date_created"),
+ )
+
+ stmt = select(logged_table.c.id).where(
+ extract("YEAR", logged_table.c.date_created) == 2021
+ )
+
+ In the above example, the statement is used to select ids from the
+ database where the ``YEAR`` component matches a specific value.
+
+ Similarly, one can also select an extracted component::
+
+ stmt = select(
+ extract("YEAR", logged_table.c.date_created)
+ ).where(logged_table.c.id == 1)
+
+ The implementation of ``EXTRACT`` may vary across database backends.
+ Users are reminded to consult their database documentation.
"""
self.type = type_api.INTEGERTYPE
self.field = field