From 68b76d12884c46bccd33bcab4cb91b97631a1649 Mon Sep 17 00:00:00 2001
From: wshwsh12 <793703860@qq.com>
Date: Fri, 26 Jul 2019 15:11:57 +0800
Subject: [PATCH] add test and fix built-in function castIntAsReal

---
 expression/builtin_cast.go     |  2 +-
 expression/integration_test.go | 23 +++++++++++++++++++++++
 go.sum                         |  8 --------
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/expression/builtin_cast.go b/expression/builtin_cast.go
index 1b8205c009118..366c48def1b80 100644
--- a/expression/builtin_cast.go
+++ b/expression/builtin_cast.go
@@ -458,7 +458,7 @@ func (b *builtinCastIntAsRealSig) evalReal(row chunk.Row) (res float64, isNull b
 	if isNull || err != nil {
 		return res, isNull, err
 	}
-	if !mysql.HasUnsignedFlag(b.tp.Flag) {
+	if !mysql.HasUnsignedFlag(b.tp.Flag) && !mysql.HasUnsignedFlag(b.args[0].GetType().Flag) {
 		res = float64(val)
 	} else if b.inUnion && val < 0 {
 		res = 0
diff --git a/expression/integration_test.go b/expression/integration_test.go
index e07ffe91fc2ac..59edab6569914 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -2330,6 +2330,29 @@ func (s *testIntegrationSuite) TestBuiltin(c *C) {
 	result = tk.MustQuery("select cast(1 as signed int)")
 	result.Check(testkit.Rows("1"))
 
+	// test cast as double
+	result = tk.MustQuery("select cast(1 as double)")
+	result.Check(testkit.Rows("1"))
+	result = tk.MustQuery("select cast(1.1 as double)")
+	result.Check(testkit.Rows("1.1"))
+	result = tk.MustQuery("select cast(1.1 as double)")
+	result.Check(testkit.Rows("1.1"))
+	result = tk.MustQuery("select cast('123.321' as double)")
+	result.Check(testkit.Rows("123.321"))
+	result = tk.MustQuery("select cast(-1 as double)")
+	result.Check(testkit.Rows("-1"))
+	result = tk.MustQuery("select cast(null as double)")
+	result.Check(testkit.Rows("<nil>"))
+	/*  There is something wrong in showing float number.
+	The testkit gets the format 'f' (-ddd.dddd, no exponent),
+	but we need the format 'e' (-d.dddde±dd, a decimal exponent).
+
+	result = tk.MustQuery("select cast(12345678901234567890 as double)")
+	result.Check(testkit.Rows("1.2345678901234567e19"))
+	result = tk.MustQuery("select cast(cast(-1 as unsigned) as double)")
+	result.Check(testkit.Rows("1.8446744073709552e19"))
+	*/
+
 	// test cast time as decimal overflow
 	tk.MustExec("drop table if exists t1")
 	tk.MustExec("create table t1(s1 time);")
diff --git a/go.sum b/go.sum
index 73cb6e7ed7912..da1a87c8df089 100644
--- a/go.sum
+++ b/go.sum
@@ -165,16 +165,8 @@ github.com/pingcap/kvproto v0.0.0-20190703131923-d9830856b531/go.mod h1:QMdbTAXC
 github.com/pingcap/log v0.0.0-20190214045112-b37da76f67a7/go.mod h1:xsfkWVaFVV5B8e1K9seWfyJWFrIhbtUTAD8NV1Pq3+w=
 github.com/pingcap/log v0.0.0-20190307075452-bd41d9273596 h1:t2OQTpPJnrPDGlvA+3FwJptMTt6MEPdzK1Wt99oaefQ=
 github.com/pingcap/log v0.0.0-20190307075452-bd41d9273596/go.mod h1:WpHUKhNZ18v116SvGrmjkA9CBhYmuUTKL+p8JC9ANEw=
-<<<<<<< HEAD
-<<<<<<< HEAD
-github.com/pingcap/parser v0.0.0-20190726023712-ca2f45b420fd h1:vFLYlcLyvWrIN+3Y9uPExiisDjeRCPh1Vic0vnkxBMs=
-github.com/pingcap/parser v0.0.0-20190726023712-ca2f45b420fd/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
-=======
->>>>>>> support cast as double
-=======
 github.com/pingcap/parser v0.0.0-20190726045944-46d1b3d054b2 h1:uPLL91Kf8Sh86ht/ijNj6iUWw7JBArTcJtyn8aR+uDs=
 github.com/pingcap/parser v0.0.0-20190726045944-46d1b3d054b2/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
->>>>>>> update mod
 github.com/pingcap/pd v0.0.0-20190712044914-75a1f9f3062b h1:oS9PftxQqgcRouKhhdaB52tXhVLEP7Ng3Qqsd6Z18iY=
 github.com/pingcap/pd v0.0.0-20190712044914-75a1f9f3062b/go.mod h1:3DlDlFT7EF64A1bmb/tulZb6wbPSagm5G4p1AlhaEDs=
 github.com/pingcap/tidb-tools v2.1.3-0.20190321065848-1e8b48f5c168+incompatible h1:MkWCxgZpJBgY2f4HtwWMMFzSBb3+JPzeJgF3VrXE/bU=