convert if eval result to correct type

Author: angelamayxie

enginetest/queries/order_by_group_by_queries.go

@@ -305,4 +305,17 @@ var OrderByGroupByScriptTests = []ScriptTest{
 			},
 		},
 	},
+	{
+		Name: "Group by true and 1",
+		SetUpScript: []string{
+			"create table t0(c0 int)",
+			"insert into t0(c0) values(1),(123)",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query:    "select if(t0.c0 = 123, TRUE, t0.c0) AS ref0, min(t0.c0) as ref1 from t0 group by ref0",
+				Expected: []sql.Row{{1, 1}},
+			},
+		},
+	},
 }

enginetest/queries/queries.go

@@ -6123,7 +6123,7 @@ SELECT * FROM cte WHERE  d = 2;`,
 	{
 		Query: `SELECT if(0, "abc", 456)`,
 		Expected: []sql.Row{
-			{456},
+			{"456"},
 		},
 	},
 	{
@@ -9696,7 +9696,7 @@ from typestable`,
 	{
 		Query: "select if('', 1, char(''));",
 		Expected: []sql.Row{
-			{[]byte{0}},
+			{"\x00"},
 		},
 	},
 	{

sql/expression/function/if.go

@@ -77,11 +77,20 @@ func (f *If) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 		}
 	}
 
+	var eval interface{}
 	if asBool {
-		return f.ifTrue.Eval(ctx, row)
+		eval, err = f.ifTrue.Eval(ctx, row)
+		if err != nil {
+			return nil, err
+		}
 	} else {
-		return f.ifFalse.Eval(ctx, row)
+		eval, err = f.ifFalse.Eval(ctx, row)
+		if err != nil {
+			return nil, err
+		}
 	}
+	eval, _, err = f.Type().Convert(ctx, eval)
+	return eval, err
 }
 
 // Type implements the Expression interface.