expression: fix the issue that incorrect result for a predicate that …

…uses the CHAR() function (#16014) (#16557)
pingcap · Apr 30, 2020 · 04baec7 · 04baec7
1 parent 0be031a
commit 04baec7
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Showing 3 changed files with 34 additions and 3 deletions.
diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -5014,3 +5014,34 @@ func (s *testIntegrationSuite) TestCacheRefineArgs(c *C) {
 	tk.MustExec("set @p0='-184467440737095516167.1'")
 	tk.MustQuery("execute stmt using @p0").Check(testkit.Rows("0"))
 }
+
+func (s *testIntegrationSuite) TestIssue15986(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t0")
+	tk.MustExec("CREATE TABLE t0(c0 int)")
+	tk.MustExec("INSERT INTO t0 VALUES (0)")
+	tk.MustQuery("SELECT t0.c0 FROM t0 WHERE CHAR(204355900);").Check(testkit.Rows("0"))
+	tk.MustQuery("SELECT t0.c0 FROM t0 WHERE not CHAR(204355900);").Check(testkit.Rows())
+	tk.MustQuery("SELECT t0.c0 FROM t0 WHERE '.0';").Check(testkit.Rows())
+	tk.MustQuery("SELECT t0.c0 FROM t0 WHERE not '.0';").Check(testkit.Rows("0"))
+	// If the number does not exceed the range of float64 and its value is not 0, it will be converted to true.
+	tk.MustQuery("select * from t0 where '.000000000000000000000000000000000000000000000000000000" +
+		"00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"0000000000000000000000000000000000000000000000000000000000000000009';").Check(testkit.Rows("0"))
+	tk.MustQuery("select * from t0 where not '.000000000000000000000000000000000000000000000000000000" +
+		"00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"0000000000000000000000000000000000000000000000000000000000000000009';").Check(testkit.Rows())
+
+	// If the number is truncated beyond the range of float64, it will be converted to true when the truncated result is 0.
+	tk.MustQuery("select * from t0 where '.0000000000000000000000000000000000000000000000000000000" +
+		"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"00000000000000000000000000000000000000000000000000000000000000000000000000000000000009';").Check(testkit.Rows())
+	tk.MustQuery("select * from t0 where not '.0000000000000000000000000000000000000000000000000000000" +
+		"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" +
+		"00000000000000000000000000000000000000000000000000000000000000000000000000000000000009';").Check(testkit.Rows("0"))
+}
diff --git a/types/datum.go b/types/datum.go
@@ -1334,7 +1334,7 @@ func (d *Datum) ToBool(sc *stmtctx.StatementContext) (int64, error) {
 	case KindFloat64:
 		isZero = RoundFloat(d.GetFloat64()) == 0
 	case KindString, KindBytes:
-		iVal, err1 := StrToInt(sc, d.GetString())
+		iVal, err1 := StrToFloat(sc, d.GetString())
 		isZero, err = iVal == 0, err1
 	case KindMysqlTime:
 		isZero = d.GetMysqlTime().IsZero()

diff --git a/types/datum_test.go b/types/datum_test.go
@@ -67,9 +67,9 @@ func (ts *testDatumSuite) TestToBool(c *C) {
 	testDatumToBool(c, float32(0.1), 0)
 	testDatumToBool(c, float64(0.1), 0)
 	testDatumToBool(c, "", 0)
-	testDatumToBool(c, "0.1", 0)
+	testDatumToBool(c, "0.1", 1)
 	testDatumToBool(c, []byte{}, 0)
-	testDatumToBool(c, []byte("0.1"), 0)
+	testDatumToBool(c, []byte("0.1"), 1)
 	testDatumToBool(c, NewBinaryLiteralFromUint(0, -1), 0)
 	testDatumToBool(c, Enum{Name: "a", Value: 1}, 1)
 	testDatumToBool(c, Set{Name: "a", Value: 1}, 1)