Column alias problem - name conflict

[bgranvea]

How to reproduce

# clickhouse-client
ClickHouse client version 20.5.4.40 (official build).
Connecting to localhost:9000 as user default.
Connected to ClickHouse server version 20.5.4 revision 54435.

> create table test1(insid UInt64, insidvalue UInt64) ENGINE=MergeTree ORDER BY tuple();     
> create table test2(insid UInt64, svalue String) ENGINE=MergeTree ORDER BY tuple();     

> SELECT NULL AS svalue FROM test1 t1 LEFT JOIN (SELECT insid,svalue FROM test2) t2 ON t1.insid=t2.insid WHERE t2.svalue='test'

Code: 47. DB::Exception: Received from localhost:9000. DB::Exception: Unknown identifier: svalue there are columns: insid.

Workaround: change column alias in select to avoid name conflict:

> SELECT NULL AS _svalue FROM test1 t1 LEFT JOIN (SELECT insid,svalue FROM test2) t2 ON t1.insid=t2.insid WHERE t2.svalue='test'
=> ok

[filimonov]

CREATE TABLE test1
(
    `insid` UInt64,
    `insidvalue` UInt64
)
ENGINE = MergeTree
ORDER BY tuple();

CREATE TABLE test2
(
    `insid` UInt64,
    `svalue` String
)
ENGINE = MergeTree
ORDER BY tuple();

SELECT NULL AS svalue
FROM test1 AS t1
LEFT JOIN 
(
    SELECT 
        insid,
        svalue
    FROM test2
) AS t2 ON t1.insid = t2.insid
WHERE t2.svalue = 'test';

Regression. Was working on <= 19.1