window function: function name of error message should be lowercase (#11047)

Author: zhaoyanxing

planner/core/logical_plan_builder.go

@@ -3134,7 +3134,7 @@ func (b *PlanBuilder) buildWindowFunctions(p LogicalPlan, groupedFuncs map[*ast.
 				return nil, nil, err
 			}
 			if desc == nil {
-				return nil, nil, ErrWrongArguments.GenWithStackByArgs(windowFunc.F)
+				return nil, nil, ErrWrongArguments.GenWithStackByArgs(strings.ToLower(windowFunc.F))
 			}
 			preArgs += len(windowFunc.Args)
 			desc.WrapCastForAggArgs(b.ctx)

planner/core/logical_plan_test.go

@@ -2285,6 +2285,10 @@ func (s *testPlanSuite) TestWindowFunction(c *C) {
 			sql:    "select nth_value(a, 1.0) over() from t",
 			result: "[planner:1210]Incorrect arguments to nth_value",
 		},
+		{
+			sql:    "SELECT NTH_VALUE(a, 1.0) OVER() FROM t",
+			result: "[planner:1210]Incorrect arguments to nth_value",
+		},
 		{
 			sql:    "select nth_value(a, 0) over() from t",
 			result: "[planner:1210]Incorrect arguments to nth_value",