From 73d3b903865146cdb595713d67da0ce67a7cffaf Mon Sep 17 00:00:00 2001
From: Ti Chi Robot <ti-community-prow-bot@tidb.io>
Date: Thu, 26 Dec 2024 16:51:48 +0800
Subject: [PATCH] expression: use maximum length for integer display (#56463)
 (#56927)

close pingcap/tidb#41719, close pingcap/tidb#45338, close pingcap/tidb#56462
---
 pkg/expression/builtin_control.go             | 23 +++++++++++++++----
 .../r/expression/issues.result                |  6 +++++
 .../integrationtest/t/expression/issues.test  |  6 +++++
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/pkg/expression/builtin_control.go b/pkg/expression/builtin_control.go
index af34824fa52e9..f592d0131252b 100644
--- a/pkg/expression/builtin_control.go
+++ b/pkg/expression/builtin_control.go
@@ -83,12 +83,25 @@ 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 {
diff --git a/tests/integrationtest/r/expression/issues.result b/tests/integrationtest/r/expression/issues.result
index ca2c8e2dcd66d..902f07aac13d4 100644
--- a/tests/integrationtest/r/expression/issues.result
+++ b/tests/integrationtest/r/expression/issues.result
@@ -3192,3 +3192,9 @@ Projection	8.00	root		test.ast.i, Column#32
       └─TableReader(Probe)	10.00	root		data:Selection
         └─Selection	10.00	cop[tikv]		eq("astp2019121731703151", test.acc.m)
           └─TableFullScan	10000.00	cop[tikv]	table:b	keep order:false, stats:pseudo
+DROP TABLE IF EXISTS test.t;
+CREATE TABLE test.t (id bigint(11) UNSIGNED PRIMARY KEY);
+INSERT INTO test.t VALUES (1234567890123456);
+SELECT IFNULL(id, 'abcdef') FROM test.t;
+IFNULL(id, 'abcdef')
+1234567890123456
diff --git a/tests/integrationtest/t/expression/issues.test b/tests/integrationtest/t/expression/issues.test
index 4c74962b84244..5b78120efd441 100644
--- a/tests/integrationtest/t/expression/issues.test
+++ b/tests/integrationtest/t/expression/issues.test
@@ -2161,3 +2161,9 @@ drop table if exists test.t;
 create table if not exists test.ast (i varchar(20));
 create table if not exists test.acc (j varchar(20), k varchar(20), l varchar(20), m varchar(20));
 explain format='brief' with t as(select i, (case when b.j = '20001' then b.l else b.k end) an from test.ast a inner join test.acc b on (a.i = b.m) and a.i = 'astp2019121731703151'), t1 as (select i, group_concat(an order by an separator '; ') an from t group by i) select * from t1;
+
+# TestIssue56462
+DROP TABLE IF EXISTS test.t;
+CREATE TABLE test.t (id bigint(11) UNSIGNED PRIMARY KEY);
+INSERT INTO test.t VALUES (1234567890123456);
+SELECT IFNULL(id, 'abcdef') FROM test.t;