From be2931dc4cba705fee9f52e0df60045aa19d1f0e Mon Sep 17 00:00:00 2001
From: ZhaoQian888 <1900022850@pku.edu.cn>
Date: Tue, 17 Dec 2019 16:47:08 +0800
Subject: [PATCH] amend

---
 expression/builtin_math_vec.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/expression/builtin_math_vec.go b/expression/builtin_math_vec.go
index 865bfe2fb452a..b5e8d7914e1d3 100644
--- a/expression/builtin_math_vec.go
+++ b/expression/builtin_math_vec.go
@@ -1087,7 +1087,7 @@ func (b *builtinConvSig) vecEvalString(input *chunk.Chunk, result *chunk.Column)
 		ignoreSign bool
 	)
 	for i := 0; i < n; i++ {
-		if buf1.IsNull(i) || buf2.IsNull(i) || buf2.IsNull(i) {
+		if buf1.IsNull(i) || buf2.IsNull(i) || buf3.IsNull(i) {
 			result.AppendNull()
 			continue
 		}