fix(mssql): ensure ibis.random() generates a new value per call

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.
 

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"),
     [