expression: fix casting year 0 to string 0000 (#21469)

pingcap · Dec 15, 2020 · 67d66d6 · 67d66d6
1 parent 25daaee
commit 67d66d6
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Showing 3 changed files with 20 additions and 2 deletions.
diff --git a/executor/executor_test.go b/executor/executor_test.go
@@ -7119,6 +7119,15 @@ func (s *testSuite) Test17780(c *C) {
 	tk.MustQuery("select count(*) from t0 where c0 = 0").Check(testkit.Rows("0"))
 }
 
+func (s *testSuite) TestIssue9918(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a year)")
+	tk.MustExec("insert into t values(0)")
+	tk.MustQuery("select cast(a as char) from t").Check(testkit.Rows("0000"))
+}
+
 func (s *testSuite) Test13004(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	// see https://dev.mysql.com/doc/refman/5.6/en/date-and-time-literals.html, timestamp here actually produces a datetime

diff --git a/expression/builtin_cast.go b/expression/builtin_cast.go
@@ -546,11 +546,15 @@ func (b *builtinCastIntAsStringSig) evalString(row chunk.Row) (res string, isNul
 	if isNull || err != nil {
 		return res, isNull, err
 	}
-	if !mysql.HasUnsignedFlag(b.args[0].GetType().Flag) {
+	tp := b.args[0].GetType()
+	if !mysql.HasUnsignedFlag(tp.Flag) {
 		res = strconv.FormatInt(val, 10)
 	} else {
 		res = strconv.FormatUint(uint64(val), 10)
 	}
+	if tp.Tp == mysql.TypeYear && res == "0" {
+		res = "0000"
+	}
 	res, err = types.ProduceStrWithSpecifiedTp(res, b.tp, b.ctx.GetSessionVars().StmtCtx, false)
 	if err != nil {
 		return res, false, err

diff --git a/expression/builtin_cast_vec.go b/expression/builtin_cast_vec.go
@@ -636,7 +636,9 @@ func (b *builtinCastIntAsStringSig) vecEvalString(input *chunk.Chunk, result *ch
 		return err
 	}
 
-	isUnsigned := mysql.HasUnsignedFlag(b.args[0].GetType().Flag)
+	tp := b.args[0].GetType()
+	isUnsigned := mysql.HasUnsignedFlag(tp.Flag)
+	isYearType := tp.Tp == mysql.TypeYear
 	result.ReserveString(n)
 	i64s := buf.Int64s()
 	for i := 0; i < n; i++ {
@@ -650,6 +652,9 @@ func (b *builtinCastIntAsStringSig) vecEvalString(input *chunk.Chunk, result *ch
 		} else {
 			str = strconv.FormatUint(uint64(i64s[i]), 10)
 		}
+		if isYearType && str == "0" {
+			str = "0000"
+		}
 		str, err = types.ProduceStrWithSpecifiedTp(str, b.tp, b.ctx.GetSessionVars().StmtCtx, false)
 		if err != nil {
 			return err