Fix pingcap#11211

expression/integration_test.go

@@ -2937,6 +2937,7 @@ func (s *testIntegrationSuite) TestArithmeticBuiltin(c *C) {
 	tk.MustExec("INSERT IGNORE INTO t VALUE(12 MOD 0);")
 	tk.MustQuery("show warnings;").Check(testkit.Rows("Warning 1365 Division by 0"))
 	tk.MustQuery("select v from t;").Check(testkit.Rows("<nil>"))
+	tk.MustQuery("select 0.000 % 0.11234500000000000000;").Check(testkit.Rows("0.00000000000000000000"))
 
 	_, err = tk.Exec("INSERT INTO t VALUE(12 MOD 0);")
 	c.Assert(terror.ErrorEqual(err, expression.ErrDivisionByZero), IsTrue)

go.sum

@@ -12,6 +12,7 @@ github.com/blacktear23/go-proxyprotocol v0.0.0-20180807104634-af7a81e8dd0d/go.mo
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20171208011716-f6d7a1f6fbf3/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
+github.com/client9/misspell v0.3.4 h1:ta993UF76GwbvJcIo3Y68y/M3WxlpEHPWIGDkJYwzJI=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd h1:qMd81Ts1T2OTKmB4acZcyKaMtRnY5Y44NuXGX2GFJ1w=
 github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd/go.mod h1:sE/e/2PUdi/liOCUjSTXgM1o87ZssimdTWN964YiIeI=
@@ -191,6 +192,7 @@ github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d h1:GoAlyOgbOEIFd
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/remyoudompheng/bigfft v0.0.0-20190512091148-babf20351dd7 h1:FUL3b97ZY2EPqg2NbXKuMHs5pXJB9hjj1fDHnF2vl28=
 github.com/remyoudompheng/bigfft v0.0.0-20190512091148-babf20351dd7/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+github.com/sergi/go-diff v1.0.1-0.20180205163309-da645544ed44 h1:tB9NOR21++IjLyVx3/PCPhWMwqGNCMQEH96A6dMZ/gc=
 github.com/sergi/go-diff v1.0.1-0.20180205163309-da645544ed44/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/shirou/gopsutil v2.18.10+incompatible h1:cy84jW6EVRPa5g9HAHrlbxMSIjBhDSX0OFYyMYminYs=
 github.com/shirou/gopsutil v2.18.10+incompatible/go.mod h1:5b4v6he4MtMOwMlS0TUMTu2PcXUg8+E1lC7eC3UO/RA=

types/mydecimal.go

@@ -2010,7 +2010,9 @@ func doDivMod(from1, from2, to, mod *MyDecimal, fracIncr int) error {
 	}
 	if prec1 <= 0 {
 		/* short-circuit everything: from1 == 0 */
+		resultFrac := to.resultFrac
 		*to = zeroMyDecimal
+		to.resultFrac = resultFrac
 		return nil
 	}
 	prec1 -= countLeadingZeroes((prec1-1)%digitsPerWord, from1.wordBuf[idx1])