From 042e61febf9cf6ac95ed3acb0d830c0a772ad941 Mon Sep 17 00:00:00 2001
From: vdimir <vdimir@clickhouse.com>
Date: Fri, 15 Oct 2021 13:53:25 +0300
Subject: [PATCH] Allow identifiers staring with numbers in multiple joins

---
 .../JoinToSubqueryTransformVisitor.cpp        |  5 ++--
 .../01120_join_constants.reference            |  2 ++
 .../0_stateless/01120_join_constants.sql      | 18 +++++++++++++
 ...96_join_unusual_identifier_begin.reference |  2 ++
 .../02096_join_unusual_identifier_begin.sql   | 27 +++++++++++++++++++
 5 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 tests/queries/0_stateless/02096_join_unusual_identifier_begin.reference
 create mode 100644 tests/queries/0_stateless/02096_join_unusual_identifier_begin.sql

diff --git a/src/Interpreters/JoinToSubqueryTransformVisitor.cpp b/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
index 3cd076f91bb..ed20b1b2048 100644
--- a/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
+++ b/src/Interpreters/JoinToSubqueryTransformVisitor.cpp
@@ -18,7 +18,7 @@
 #include <Parsers/parseQuery.h>
 #include <IO/WriteHelpers.h>
 #include <Core/Defines.h>
-
+#include <Common/StringUtils/StringUtils.h>
 
 namespace DB
 {
@@ -524,7 +524,8 @@ std::vector<TableNeededColumns> normalizeColumnNamesExtractNeeded(
 
                 size_t count = countTablesWithColumn(tables, short_name);
 
-                if (count > 1 || aliases.count(short_name))
+                /// isValidIdentifierBegin retuired to be consistent with TableJoin::deduplicateAndQualifyColumnNames
+                if (count > 1 || aliases.count(short_name) || !isValidIdentifierBegin(short_name.at(0)))
                 {
                     const auto & table = tables[*table_pos];
                     IdentifierSemantic::setColumnLongName(*ident, table.table); /// table.column -> table_alias.column
diff --git a/tests/queries/0_stateless/01120_join_constants.reference b/tests/queries/0_stateless/01120_join_constants.reference
index a16427fbdf7..91838e7a2bb 100644
--- a/tests/queries/0_stateless/01120_join_constants.reference
+++ b/tests/queries/0_stateless/01120_join_constants.reference
@@ -1,2 +1,4 @@
 1	hello	1	world	world	1
 2	hello	0		world	1
+1	321	1	123	123	1
+2	321	0	0	123	1
diff --git a/tests/queries/0_stateless/01120_join_constants.sql b/tests/queries/0_stateless/01120_join_constants.sql
index 443559c3ea1..d6d6a1be43b 100644
--- a/tests/queries/0_stateless/01120_join_constants.sql
+++ b/tests/queries/0_stateless/01120_join_constants.sql
@@ -15,3 +15,21 @@ LEFT JOIN
         arrayJoin([1, 3]) AS k,
         'world'
 ) AS t2 ON t1.k = t2.k;
+
+SELECT
+    t1.*,
+    t2.*,
+    123,
+    isConstant('world')
+FROM
+(
+    SELECT
+        arrayJoin([1, 2]) AS k,
+        321
+) AS t1
+LEFT JOIN
+(
+    SELECT
+        arrayJoin([1, 3]) AS k,
+        123
+) AS t2 ON t1.k = t2.k;
diff --git a/tests/queries/0_stateless/02096_join_unusual_identifier_begin.reference b/tests/queries/0_stateless/02096_join_unusual_identifier_begin.reference
new file mode 100644
index 00000000000..e8cc5e526c0
--- /dev/null
+++ b/tests/queries/0_stateless/02096_join_unusual_identifier_begin.reference
@@ -0,0 +1,2 @@
+1	1	1	1	1	1
+1
diff --git a/tests/queries/0_stateless/02096_join_unusual_identifier_begin.sql b/tests/queries/0_stateless/02096_join_unusual_identifier_begin.sql
new file mode 100644
index 00000000000..fc6be2eff7b
--- /dev/null
+++ b/tests/queries/0_stateless/02096_join_unusual_identifier_begin.sql
@@ -0,0 +1,27 @@
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP TABLE IF EXISTS t3;
+
+CREATE TABLE t1 ( `a1` Int64, `1a1` Int64 ) ENGINE = Memory;
+INSERT INTO t1 VALUES (1, 1);
+
+CREATE TABLE t2 ( `b1` Int64, `1b1` Int64 ) ENGINE = Memory;
+INSERT INTO t2 VALUES (1, 1);
+
+CREATE TABLE t3 ( `c1` Int64, `1c1` Int64 ) ENGINE = Memory;
+INSERT INTO t3 VALUES (1, 1);
+
+SELECT
+    *
+FROM t1 AS t1
+INNER JOIN t2 AS t2 ON t1.a1 = t2.b1
+INNER JOIN t3 AS t3 ON t1.a1 = t3.c1;
+
+SELECT t2.`1b1` FROM t1 JOIN t2 ON a1 = b1;
+
+-- Without quialification it doesn't work:
+-- SELECT `1b1` FROM t1 JOIN t2 ON a1 = b1;
+
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP TABLE IF EXISTS t3;