From 370a12ff9813207eb99d10a411ab0d2aecc3a0bc Mon Sep 17 00:00:00 2001
From: pingcap-github-bot <sre-bot@pingcap.com>
Date: Thu, 9 Apr 2020 11:50:08 +0800
Subject: [PATCH] executor: fix unexpected error in union stmt. (#16073)
 (#16138)

---
 executor/executor.go           |  6 ++++++
 expression/integration_test.go | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/executor/executor.go b/executor/executor.go
index 9e32321591408..71d443f9c02e1 100644
--- a/executor/executor.go
+++ b/executor/executor.go
@@ -1563,6 +1563,12 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
 			sc.NotFillCache = !opts.SQLCache
 		}
 		sc.CastStrToIntStrict = true
+	case *ast.UnionStmt:
+		sc.InSelectStmt = true
+		sc.OverflowAsWarning = true
+		sc.TruncateAsWarning = true
+		sc.IgnoreZeroInDate = true
+		sc.AllowInvalidDate = vars.SQLMode.HasAllowInvalidDatesMode()
 	case *ast.ShowStmt:
 		sc.IgnoreTruncate = true
 		sc.IgnoreZeroInDate = true
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 0f999d560103f..4e85839970331 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -4918,3 +4918,13 @@ func (s *testIntegrationSuite) TestValuesForBinaryLiteral(c *C) {
 	tk.MustQuery("select a=0 from testValuesBinary;").Check(testkit.Rows("1"))
 	tk.MustExec("drop table testValuesBinary;")
 }
+
+func (s *testIntegrationSuite) TestIssue15790(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test;")
+	tk.MustExec("CREATE TABLE t0(c0 INT);")
+	tk.MustExec("INSERT INTO t0(c0) VALUES (0);")
+	tk.MustQuery("SELECT * FROM t0 WHERE -10000000000000000000 | t0.c0 UNION SELECT * FROM t0;").Check(testkit.Rows("0"))
+	tk.MustQuery("SELECT * FROM t0 WHERE -10000000000000000000 | t0.c0 UNION all SELECT * FROM t0;").Check(testkit.Rows("0", "0"))
+	tk.MustExec("drop table t0;")
+}