From f1d35cc57bd5bf92995ce09995593deffc9fc1b9 Mon Sep 17 00:00:00 2001
From: Jim Crist-Harif <jcristharif@gmail.com>
Date: Thu, 19 Sep 2024 14:02:01 -0500
Subject: [PATCH] fix(mssql): ensure `ibis.random()` generates a new value per
 call

---
 ibis/backends/sql/compilers/mssql.py |  6 ++++++
 ibis/backends/tests/test_numeric.py  | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/ibis/backends/sql/compilers/mssql.py b/ibis/backends/sql/compilers/mssql.py
index 70215fed821ac..dbb0e3f9fe2c3 100644
--- a/ibis/backends/sql/compilers/mssql.py
+++ b/ibis/backends/sql/compilers/mssql.py
@@ -171,6 +171,12 @@ def to_sqlglot(
     def visit_RandomUUID(self, op, **_):
         return self.f.newid()
 
+    def visit_RandomScalar(self, op, **_):
+        # By default RAND() will generate the same value for all calls within a
+        # query. The standard way to work around this is to pass in a unique
+        # value per call, which `CHECKSUM(NEWID())` provides.
+        return self.f.rand(self.f.checksum(self.f.newid()))
+
     def visit_StringLength(self, op, *, arg):
         """The MSSQL LEN function doesn't count trailing spaces.
 
diff --git a/ibis/backends/tests/test_numeric.py b/ibis/backends/tests/test_numeric.py
index d5c16e9d08ac1..4d23680c7cf40 100644
--- a/ibis/backends/tests/test_numeric.py
+++ b/ibis/backends/tests/test_numeric.py
@@ -1309,6 +1309,18 @@ def test_random(con):
     assert 0 <= result <= 1
 
 
+@pytest.mark.notimpl(["polars"], raises=com.OperationNotDefinedError)
+@pytest.mark.notimpl(["druid"], raises=PyDruidProgrammingError)
+@pytest.mark.notimpl(
+    ["risingwave"],
+    raises=PsycoPg2InternalError,
+    reason="function random() does not exist",
+)
+def test_random_different_per_row(alltypes):
+    result = alltypes.select("int_col", rand_col=ibis.random()).execute()
+    assert result.rand_col.nunique() > 1
+
+
 @pytest.mark.parametrize(
     ("ibis_func", "pandas_func"),
     [