expression: use maximum length for integer display (pingcap#56463) (pingcap#56929)

close pingcap#41719, close pingcap#45338, close pingcap#56462

Author: ti-chi-bot

pkg/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 {

tests/integrationtest/r/expression/issues.result

@@ -2814,3 +2814,9 @@ SELECT @@GLOBAL.information_schema_stats_expiry;
 0
 set @@SESSION.information_schema_stats_expiry=default;
 set @@GLOBAL.information_schema_stats_expiry=default;
+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

tests/integrationtest/t/expression/issues.test

@@ -1918,3 +1918,9 @@ SELECT @@GLOBAL.information_schema_stats_expiry;
 SELECT @@GLOBAL.information_schema_stats_expiry;
 set @@SESSION.information_schema_stats_expiry=default;
 set @@GLOBAL.information_schema_stats_expiry=default;
+
+# 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;