expression: unset the flen for string type builtin control (#38845)

close #38844
pingcap · Nov 3, 2022 · cacd3c8 · cacd3c8
1 parent 3baebdb
commit cacd3c8
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Showing 2 changed files with 16 additions and 0 deletions.
diff --git a/expression/builtin_control.go b/expression/builtin_control.go
@@ -146,6 +146,11 @@ func InferType4ControlFuncs(ctx sessionctx.Context, funcName string, lexp, rexp
 			}
 			flen := maxlen(lhsFlen, rhsFlen) + resultFieldType.GetDecimal() + 1 // account for -1 len fields
 			resultFieldType.SetFlenUnderLimit(flen)
+		} else if evalType == types.ETString {
+			lhsLen, rhsLen := lhs.GetFlen(), rhs.GetFlen()
+			if lhsLen != types.UnspecifiedLength && rhsLen != types.UnspecifiedLength {
+				resultFieldType.SetFlen(mathutil.Max(lhsLen, rhsLen))
+			}
 		} else {
 			resultFieldType.SetFlen(maxlen(lhs.GetFlen(), rhs.GetFlen()))
 		}

diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -7805,3 +7805,14 @@ func TestJSONExtractRange(t *testing.T) {
 	tk.MustQuery(`select json_extract('[{"a": [1,2,3,4]}]', '$[0].a[0 to last]')`).Check(testkit.Rows("[1, 2, 3, 4]"))
 	tk.MustQuery(`select json_extract('[{"a": [1,2,3,4]}]', '$[0].a[0 to 2]')`).Check(testkit.Rows("[1, 2, 3]"))
 }
+
+func TestIfNullParamMarker(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (c1 varchar(100), c2 varchar(128));")
+	tk.MustExec(`prepare pr1 from "insert into t values(ifnull(?,' '),ifnull(?,' '))";`)
+	tk.MustExec(`set @a='1',@b=repeat('x', 80);`)
+	// Should not report 'Data too long for column' error.
+	tk.MustExec(`execute pr1 using @a,@b;`)
+}