From 8003f50c472256f081866344bdf3559dac749ee7 Mon Sep 17 00:00:00 2001
From: Ti Chi Robot <ti-community-prow-bot@tidb.io>
Date: Mon, 11 Nov 2024 16:44:27 +0800
Subject: [PATCH] expression: use maximum length for integer display (#56463)
 (#56926)

close pingcap/tidb#41719, close pingcap/tidb#45338, close pingcap/tidb#56462
---
 expression/builtin_control.go | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/expression/builtin_control.go b/expression/builtin_control.go
index ac2d21d0044b9..7e38e1bab8375 100644
--- a/expression/builtin_control.go
+++ b/expression/builtin_control.go
@@ -84,12 +84,25 @@ func setFlenFromArgs(evalType types.EvalType, resultFieldType *types.FieldType,
 	} else if evalType == types.ETString {
 		maxLen := 0
 		for i := range argTps {
-			argFlen := argTps[i].GetFlen()
-			if argFlen == types.UnspecifiedLength {
-				resultFieldType.SetFlen(types.UnspecifiedLength)
-				return
+			switch argTps[i].GetType() {
+			case mysql.TypeTiny:
+				maxLen = maxlen(4, maxLen)
+			case mysql.TypeShort:
+				maxLen = maxlen(6, maxLen)
+			case mysql.TypeInt24:
+				maxLen = maxlen(9, maxLen)
+			case mysql.TypeLong:
+				maxLen = maxlen(11, maxLen)
+			case mysql.TypeLonglong:
+				maxLen = maxlen(20, maxLen)
+			default:
+				argFlen := argTps[i].GetFlen()
+				if argFlen == types.UnspecifiedLength {
+					resultFieldType.SetFlen(types.UnspecifiedLength)
+					return
+				}
+				maxLen = maxlen(argFlen, maxLen)
 			}
-			maxLen = maxlen(argFlen, maxLen)
 		}
 		resultFieldType.SetFlen(maxLen)
 	} else {