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Posted to dev@calcite.apache.org by JiaTao Tao <ta...@apache.org> on 2020/02/19 06:17:52 UTC
How to trace a column back to its original column
SQL like this:
```
SELECT T1.NID,
T1.NAME,
T2.COMPANY
FROM
(SELECT (U.ID +100) AS NID,
U.NAME AS NAME
FROM USERS U) T1
JOIN
(SELECT (J.ID +100) AS NID,
J.COMPANY
FROM JOBS J) T2 ON T1.NID = T2.NID
```
What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
USER.NAME.
Has anyone done similar work? Is there a ready-made example to refer to?
Regards!
Aron Tao
Re: How to trace a column back to its original column
Posted by Rui Wang <am...@apache.org>.
If you have to traverse the whole AST/Rel tree to find original columns,
this thread discussed that before:
https://lists.apache.org/thread.html/11b66dd7f389f0b6e6bce54ad2d7b49a8a0bdd3be4784c441bfafb81%40%3Cdev.calcite.apache.org%3E
-Rui
On Wed, Feb 19, 2020 at 7:16 AM Seliverstov Igor <gv...@gmail.com>
wrote:
> This case each NID column is a calculated value - origin erases.
>
> You may try to infer origin walking through SQL AST recursively
>
> I can’t come up with another way.
>
> Regards,
> Igor
>
> > 19 февр. 2020 г., в 15:02, JiaTao Tao <ta...@gmail.com> написал(а):
> >
> > Thanks a lot
> >
> > But I found if the select is from the subquery, `getFieldOrigins`
> returns null, because you can not find the table(see in the pic.).
> > String sql = "SELECT T1.NAME <http://t1.name/>,\n"
> > + " T1.NID,\n"
> > + " T2.NID,\n"
> > + " T2.COMPANY\n"
> > + "FROM\n"
> > + " (SELECT (U.ID <http://u.id/> +100) AS NID,\n"
> > + " U.NAME <http://u.name/> AS NAME\n"
> > + " FROM USERS U) T1\n"
> > + "JOIN\n"
> > + " (SELECT (J.ID <http://j.id/> +100) AS NID,\n"
> > + " J.COMPANY\n"
> > + " FROM JOBS J) T2 ON T1.NID = T2.NID";
> >
> >
> > Regards!
> > Aron Tao
> >
> >
> > Seliverstov Igor <gvvinblade@gmail.com <ma...@gmail.com>>
> 于2020年2月19日周三 下午5:38写道：
> > Aron Tao,
> >
> > I think you need the next two methods:
> >
> > org.apache.calcite.sql.validate.SqlValidatorImpl#getFieldOrigins
> > java.sql.ResultSetMetaData#getTableName
> >
> > Regards,
> > Igor
> >
> > > 19 февр. 2020 г., в 10:29, JiaTao Tao <taojiatao@gmail.com <mailto:
> taojiatao@gmail.com>> написал(а):
> > >
> > > Hi
> > > Thanks a lot.
> > > Can you give more details, say which method/field?
> > >
> > > Regards!
> > >
> > > Aron Tao
> > >
> > >
> > > Seliverstov Igor <gvvinblade@gmail.com <ma...@gmail.com>>
> 于2020年2月19日周三 下午2:31写道：
> > >
> > >> You can use their origins (says where a column came from).
> > >>
> > >> It's accessable from SqlValidatorImpl or jdbc result set
> > >>
> > >> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <tao@apache.org <mailto:
> tao@apache.org>>:
> > >>
> > >>> What I really need is to collect every part of the SQL, Which
> columns are
> > >>> used as filters, which are used as projection(Columns on the source
> > >>> table), But
> > >>> the existence of nested subqueries complicates the issue.
> > >>>
> > >>>
> > >>> Regards!
> > >>>
> > >>> Aron Tao
> > >>>
> > >>>
> > >>> JiaTao Tao <tao@apache.org <ma...@apache.org>> 于2020年2月19日周三
> 下午2:17写道：
> > >>>
> > >>>> SQL like this:
> > >>>> ```
> > >>>> SELECT T1.NID,
> > >>>> T1.NAME <http://t1.name/>,
> > >>>> T2.COMPANY
> > >>>> FROM
> > >>>> (SELECT (U.ID <http://u.id/> +100) AS NID,
> > >>>> U.NAME <http://u.name/> AS NAME
> > >>>> FROM USERS U) T1
> > >>>> JOIN
> > >>>> (SELECT (J.ID <http://j.id/> +100) AS NID,
> > >>>> J.COMPANY
> > >>>> FROM JOBS J) T2 ON T1.NID = T2.NID
> > >>>> ```
> > >>>> What I wanted is that T1.NID comes from USER.ID <http://user.id/>,
> T1.NAME <http://t1.name/> comes from
> > >>>> USER.NAME <http://user.name/>.
> > >>>>
> > >>>> Has anyone done similar work? Is there a ready-made example to refer
> > >> to?
> > >>>>
> > >>>>
> > >>>> Regards!
> > >>>>
> > >>>> Aron Tao
> > >>>>
> > >>>
> > >>
> >
>
>
Re: How to trace a column back to its original column
Posted by JiaTao Tao <ta...@gmail.com>.
Hi Igor
org.apache.calcite.rel.metadata.RelMetadataQuery#getColumnOrigins may help
Regards!
Aron Tao
Seliverstov Igor <gv...@gmail.com> 于2020年2月19日周三 下午11:16写道：
> This case each NID column is a calculated value - origin erases.
>
> You may try to infer origin walking through SQL AST recursively
>
> I can’t come up with another way.
>
> Regards,
> Igor
>
> > 19 февр. 2020 г., в 15:02, JiaTao Tao <ta...@gmail.com> написал(а):
> >
> > Thanks a lot
> >
> > But I found if the select is from the subquery, `getFieldOrigins`
> returns null, because you can not find the table(see in the pic.).
> > String sql = "SELECT T1.NAME <http://t1.name/>,\n"
> > + " T1.NID,\n"
> > + " T2.NID,\n"
> > + " T2.COMPANY\n"
> > + "FROM\n"
> > + " (SELECT (U.ID <http://u.id/> +100) AS NID,\n"
> > + " U.NAME <http://u.name/> AS NAME\n"
> > + " FROM USERS U) T1\n"
> > + "JOIN\n"
> > + " (SELECT (J.ID <http://j.id/> +100) AS NID,\n"
> > + " J.COMPANY\n"
> > + " FROM JOBS J) T2 ON T1.NID = T2.NID";
> >
> >
> > Regards!
> > Aron Tao
> >
> >
> > Seliverstov Igor <gvvinblade@gmail.com <ma...@gmail.com>>
> 于2020年2月19日周三 下午5:38写道：
> > Aron Tao,
> >
> > I think you need the next two methods:
> >
> > org.apache.calcite.sql.validate.SqlValidatorImpl#getFieldOrigins
> > java.sql.ResultSetMetaData#getTableName
> >
> > Regards,
> > Igor
> >
> > > 19 февр. 2020 г., в 10:29, JiaTao Tao <taojiatao@gmail.com <mailto:
> taojiatao@gmail.com>> написал(а):
> > >
> > > Hi
> > > Thanks a lot.
> > > Can you give more details, say which method/field?
> > >
> > > Regards!
> > >
> > > Aron Tao
> > >
> > >
> > > Seliverstov Igor <gvvinblade@gmail.com <ma...@gmail.com>>
> 于2020年2月19日周三 下午2:31写道：
> > >
> > >> You can use their origins (says where a column came from).
> > >>
> > >> It's accessable from SqlValidatorImpl or jdbc result set
> > >>
> > >> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <tao@apache.org <mailto:
> tao@apache.org>>:
> > >>
> > >>> What I really need is to collect every part of the SQL, Which
> columns are
> > >>> used as filters, which are used as projection(Columns on the source
> > >>> table), But
> > >>> the existence of nested subqueries complicates the issue.
> > >>>
> > >>>
> > >>> Regards!
> > >>>
> > >>> Aron Tao
> > >>>
> > >>>
> > >>> JiaTao Tao <tao@apache.org <ma...@apache.org>> 于2020年2月19日周三
> 下午2:17写道：
> > >>>
> > >>>> SQL like this:
> > >>>> ```
> > >>>> SELECT T1.NID,
> > >>>> T1.NAME <http://t1.name/>,
> > >>>> T2.COMPANY
> > >>>> FROM
> > >>>> (SELECT (U.ID <http://u.id/> +100) AS NID,
> > >>>> U.NAME <http://u.name/> AS NAME
> > >>>> FROM USERS U) T1
> > >>>> JOIN
> > >>>> (SELECT (J.ID <http://j.id/> +100) AS NID,
> > >>>> J.COMPANY
> > >>>> FROM JOBS J) T2 ON T1.NID = T2.NID
> > >>>> ```
> > >>>> What I wanted is that T1.NID comes from USER.ID <http://user.id/>,
> T1.NAME <http://t1.name/> comes from
> > >>>> USER.NAME <http://user.name/>.
> > >>>>
> > >>>> Has anyone done similar work? Is there a ready-made example to refer
> > >> to?
> > >>>>
> > >>>>
> > >>>> Regards!
> > >>>>
> > >>>> Aron Tao
> > >>>>
> > >>>
> > >>
> >
>
>
Re: How to trace a column back to its original column
Posted by Seliverstov Igor <gv...@gmail.com>.
This case each NID column is a calculated value - origin erases.
You may try to infer origin walking through SQL AST recursively
I can’t come up with another way.
Regards,
Igor
> 19 февр. 2020 г., в 15:02, JiaTao Tao <ta...@gmail.com> написал(а):
>
> Thanks a lot
>
> But I found if the select is from the subquery, `getFieldOrigins` returns null, because you can not find the table(see in the pic.).
> String sql = "SELECT T1.NAME <http://t1.name/>,\n"
> + " T1.NID,\n"
> + " T2.NID,\n"
> + " T2.COMPANY\n"
> + "FROM\n"
> + " (SELECT (U.ID <http://u.id/> +100) AS NID,\n"
> + " U.NAME <http://u.name/> AS NAME\n"
> + " FROM USERS U) T1\n"
> + "JOIN\n"
> + " (SELECT (J.ID <http://j.id/> +100) AS NID,\n"
> + " J.COMPANY\n"
> + " FROM JOBS J) T2 ON T1.NID = T2.NID";
>
>
> Regards!
> Aron Tao
>
>
> Seliverstov Igor <gvvinblade@gmail.com <ma...@gmail.com>> 于2020年2月19日周三 下午5:38写道：
> Aron Tao,
>
> I think you need the next two methods:
>
> org.apache.calcite.sql.validate.SqlValidatorImpl#getFieldOrigins
> java.sql.ResultSetMetaData#getTableName
>
> Regards,
> Igor
>
> > 19 февр. 2020 г., в 10:29, JiaTao Tao <taojiatao@gmail.com <ma...@gmail.com>> написал(а):
> >
> > Hi
> > Thanks a lot.
> > Can you give more details, say which method/field?
> >
> > Regards!
> >
> > Aron Tao
> >
> >
> > Seliverstov Igor <gvvinblade@gmail.com <ma...@gmail.com>> 于2020年2月19日周三 下午2:31写道：
> >
> >> You can use their origins (says where a column came from).
> >>
> >> It's accessable from SqlValidatorImpl or jdbc result set
> >>
> >> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <tao@apache.org <ma...@apache.org>>:
> >>
> >>> What I really need is to collect every part of the SQL, Which columns are
> >>> used as filters, which are used as projection(Columns on the source
> >>> table), But
> >>> the existence of nested subqueries complicates the issue.
> >>>
> >>>
> >>> Regards!
> >>>
> >>> Aron Tao
> >>>
> >>>
> >>> JiaTao Tao <tao@apache.org <ma...@apache.org>> 于2020年2月19日周三 下午2:17写道：
> >>>
> >>>> SQL like this:
> >>>> ```
> >>>> SELECT T1.NID,
> >>>> T1.NAME <http://t1.name/>,
> >>>> T2.COMPANY
> >>>> FROM
> >>>> (SELECT (U.ID <http://u.id/> +100) AS NID,
> >>>> U.NAME <http://u.name/> AS NAME
> >>>> FROM USERS U) T1
> >>>> JOIN
> >>>> (SELECT (J.ID <http://j.id/> +100) AS NID,
> >>>> J.COMPANY
> >>>> FROM JOBS J) T2 ON T1.NID = T2.NID
> >>>> ```
> >>>> What I wanted is that T1.NID comes from USER.ID <http://user.id/>, T1.NAME <http://t1.name/> comes from
> >>>> USER.NAME <http://user.name/>.
> >>>>
> >>>> Has anyone done similar work? Is there a ready-made example to refer
> >> to?
> >>>>
> >>>>
> >>>> Regards!
> >>>>
> >>>> Aron Tao
> >>>>
> >>>
> >>
>
Re: How to trace a column back to its original column
Posted by JiaTao Tao <ta...@gmail.com>.
Thanks a lot
But I found if the select is from the subquery, `getFieldOrigins` returns
null, because you can not find the table(see in the pic.).
String sql = "SELECT T1.NAME,\n"
+ " T1.NID,\n"
+ " T2.NID,\n"
+ " T2.COMPANY\n"
+ "FROM\n"
+ " (SELECT (U.ID +100) AS NID,\n"
+ " U.NAME AS NAME\n"
+ " FROM USERS U) T1\n"
+ "JOIN\n"
+ " (SELECT (J.ID +100) AS NID,\n"
+ " J.COMPANY\n"
+ " FROM JOBS J) T2 ON T1.NID = T2.NID";
[image: image.png]
Regards!
Aron Tao
Seliverstov Igor <gv...@gmail.com> 于2020年2月19日周三 下午5:38写道：
> Aron Tao,
>
> I think you need the next two methods:
>
> org.apache.calcite.sql.validate.SqlValidatorImpl#getFieldOrigins
> java.sql.ResultSetMetaData#getTableName
>
> Regards,
> Igor
>
> > 19 февр. 2020 г., в 10:29, JiaTao Tao <ta...@gmail.com> написал(а):
> >
> > Hi
> > Thanks a lot.
> > Can you give more details, say which method/field?
> >
> > Regards!
> >
> > Aron Tao
> >
> >
> > Seliverstov Igor <gv...@gmail.com> 于2020年2月19日周三 下午2:31写道：
> >
> >> You can use their origins (says where a column came from).
> >>
> >> It's accessable from SqlValidatorImpl or jdbc result set
> >>
> >> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <ta...@apache.org>:
> >>
> >>> What I really need is to collect every part of the SQL, Which columns
> are
> >>> used as filters, which are used as projection(Columns on the source
> >>> table), But
> >>> the existence of nested subqueries complicates the issue.
> >>>
> >>>
> >>> Regards!
> >>>
> >>> Aron Tao
> >>>
> >>>
> >>> JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
> >>>
> >>>> SQL like this:
> >>>> ```
> >>>> SELECT T1.NID,
> >>>> T1.NAME,
> >>>> T2.COMPANY
> >>>> FROM
> >>>> (SELECT (U.ID +100) AS NID,
> >>>> U.NAME AS NAME
> >>>> FROM USERS U) T1
> >>>> JOIN
> >>>> (SELECT (J.ID +100) AS NID,
> >>>> J.COMPANY
> >>>> FROM JOBS J) T2 ON T1.NID = T2.NID
> >>>> ```
> >>>> What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
> >>>> USER.NAME.
> >>>>
> >>>> Has anyone done similar work? Is there a ready-made example to refer
> >> to?
> >>>>
> >>>>
> >>>> Regards!
> >>>>
> >>>> Aron Tao
> >>>>
> >>>
> >>
>
>
Re: How to trace a column back to its original column
Posted by Seliverstov Igor <gv...@gmail.com>.
Aron Tao,
I think you need the next two methods:
org.apache.calcite.sql.validate.SqlValidatorImpl#getFieldOrigins
java.sql.ResultSetMetaData#getTableName
Regards,
Igor
> 19 февр. 2020 г., в 10:29, JiaTao Tao <ta...@gmail.com> написал(а):
>
> Hi
> Thanks a lot.
> Can you give more details, say which method/field?
>
> Regards!
>
> Aron Tao
>
>
> Seliverstov Igor <gv...@gmail.com> 于2020年2月19日周三 下午2:31写道：
>
>> You can use their origins (says where a column came from).
>>
>> It's accessable from SqlValidatorImpl or jdbc result set
>>
>> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <ta...@apache.org>:
>>
>>> What I really need is to collect every part of the SQL, Which columns are
>>> used as filters, which are used as projection(Columns on the source
>>> table), But
>>> the existence of nested subqueries complicates the issue.
>>>
>>>
>>> Regards!
>>>
>>> Aron Tao
>>>
>>>
>>> JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
>>>
>>>> SQL like this:
>>>> ```
>>>> SELECT T1.NID,
>>>> T1.NAME,
>>>> T2.COMPANY
>>>> FROM
>>>> (SELECT (U.ID +100) AS NID,
>>>> U.NAME AS NAME
>>>> FROM USERS U) T1
>>>> JOIN
>>>> (SELECT (J.ID +100) AS NID,
>>>> J.COMPANY
>>>> FROM JOBS J) T2 ON T1.NID = T2.NID
>>>> ```
>>>> What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
>>>> USER.NAME.
>>>>
>>>> Has anyone done similar work? Is there a ready-made example to refer
>> to?
>>>>
>>>>
>>>> Regards!
>>>>
>>>> Aron Tao
>>>>
>>>
>>
Re: How to trace a column back to its original column
Posted by JiaTao Tao <ta...@gmail.com>.
Hi
Thanks a lot.
Can you give more details, say which method/field?
Regards!
Aron Tao
Seliverstov Igor <gv...@gmail.com> 于2020年2月19日周三 下午2:31写道：
> You can use their origins (says where a column came from).
>
> It's accessable from SqlValidatorImpl or jdbc result set
>
> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <ta...@apache.org>:
>
> > What I really need is to collect every part of the SQL, Which columns are
> > used as filters, which are used as projection(Columns on the source
> > table), But
> > the existence of nested subqueries complicates the issue.
> >
> >
> > Regards!
> >
> > Aron Tao
> >
> >
> > JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
> >
> > > SQL like this:
> > > ```
> > > SELECT T1.NID,
> > > T1.NAME,
> > > T2.COMPANY
> > > FROM
> > > (SELECT (U.ID +100) AS NID,
> > > U.NAME AS NAME
> > > FROM USERS U) T1
> > > JOIN
> > > (SELECT (J.ID +100) AS NID,
> > > J.COMPANY
> > > FROM JOBS J) T2 ON T1.NID = T2.NID
> > > ```
> > > What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
> > > USER.NAME.
> > >
> > > Has anyone done similar work? Is there a ready-made example to refer
> to?
> > >
> > >
> > > Regards!
> > >
> > > Aron Tao
> > >
> >
>
Re: How to trace a column back to its original column
Posted by JiaTao Tao <ta...@gmail.com>.
Thanks a lot!
seems I can use
org.apache.calcite.rel.metadata.RelMetadataQuery#getColumnOrigin.
Regards!
Aron Tao
Walaa Eldin Moustafa <wa...@gmail.com> 于2020年2月19日周三 下午2:36写道：
> You might check out this class [1].
>
> [1]
> https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/metadata/RelMdExpressionLineage.java
>
> On Tue, Feb 18, 2020 at 10:31 PM Seliverstov Igor <gv...@gmail.com>
> wrote:
> >
> > You can use their origins (says where a column came from).
> >
> > It's accessable from SqlValidatorImpl or jdbc result set
> >
> > ср, 19 февр. 2020 г., 9:25 JiaTao Tao <ta...@apache.org>:
> >
> > > What I really need is to collect every part of the SQL, Which columns
> are
> > > used as filters, which are used as projection(Columns on the source
> > > table), But
> > > the existence of nested subqueries complicates the issue.
> > >
> > >
> > > Regards!
> > >
> > > Aron Tao
> > >
> > >
> > > JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
> > >
> > > > SQL like this:
> > > > ```
> > > > SELECT T1.NID,
> > > > T1.NAME,
> > > > T2.COMPANY
> > > > FROM
> > > > (SELECT (U.ID +100) AS NID,
> > > > U.NAME AS NAME
> > > > FROM USERS U) T1
> > > > JOIN
> > > > (SELECT (J.ID +100) AS NID,
> > > > J.COMPANY
> > > > FROM JOBS J) T2 ON T1.NID = T2.NID
> > > > ```
> > > > What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
> > > > USER.NAME.
> > > >
> > > > Has anyone done similar work? Is there a ready-made example to refer
> to?
> > > >
> > > >
> > > > Regards!
> > > >
> > > > Aron Tao
> > > >
> > >
>
Re: How to trace a column back to its original column
Posted by Walaa Eldin Moustafa <wa...@gmail.com>.
You might check out this class [1].
[1] https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/metadata/RelMdExpressionLineage.java
On Tue, Feb 18, 2020 at 10:31 PM Seliverstov Igor <gv...@gmail.com> wrote:
>
> You can use their origins (says where a column came from).
>
> It's accessable from SqlValidatorImpl or jdbc result set
>
> ср, 19 февр. 2020 г., 9:25 JiaTao Tao <ta...@apache.org>:
>
> > What I really need is to collect every part of the SQL, Which columns are
> > used as filters, which are used as projection(Columns on the source
> > table), But
> > the existence of nested subqueries complicates the issue.
> >
> >
> > Regards!
> >
> > Aron Tao
> >
> >
> > JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
> >
> > > SQL like this:
> > > ```
> > > SELECT T1.NID,
> > > T1.NAME,
> > > T2.COMPANY
> > > FROM
> > > (SELECT (U.ID +100) AS NID,
> > > U.NAME AS NAME
> > > FROM USERS U) T1
> > > JOIN
> > > (SELECT (J.ID +100) AS NID,
> > > J.COMPANY
> > > FROM JOBS J) T2 ON T1.NID = T2.NID
> > > ```
> > > What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
> > > USER.NAME.
> > >
> > > Has anyone done similar work? Is there a ready-made example to refer to?
> > >
> > >
> > > Regards!
> > >
> > > Aron Tao
> > >
> >
Re: How to trace a column back to its original column
Posted by Seliverstov Igor <gv...@gmail.com>.
You can use their origins (says where a column came from).
It's accessable from SqlValidatorImpl or jdbc result set
ср, 19 февр. 2020 г., 9:25 JiaTao Tao <ta...@apache.org>:
> What I really need is to collect every part of the SQL, Which columns are
> used as filters, which are used as projection(Columns on the source
> table), But
> the existence of nested subqueries complicates the issue.
>
>
> Regards!
>
> Aron Tao
>
>
> JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
>
> > SQL like this:
> > ```
> > SELECT T1.NID,
> > T1.NAME,
> > T2.COMPANY
> > FROM
> > (SELECT (U.ID +100) AS NID,
> > U.NAME AS NAME
> > FROM USERS U) T1
> > JOIN
> > (SELECT (J.ID +100) AS NID,
> > J.COMPANY
> > FROM JOBS J) T2 ON T1.NID = T2.NID
> > ```
> > What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
> > USER.NAME.
> >
> > Has anyone done similar work? Is there a ready-made example to refer to?
> >
> >
> > Regards!
> >
> > Aron Tao
> >
>
Re: How to trace a column back to its original column
Posted by JiaTao Tao <ta...@apache.org>.
What I really need is to collect every part of the SQL, Which columns are
used as filters, which are used as projection(Columns on the source table), But
the existence of nested subqueries complicates the issue.
Regards!
Aron Tao
JiaTao Tao <ta...@apache.org> 于2020年2月19日周三 下午2:17写道：
> SQL like this:
> ```
> SELECT T1.NID,
> T1.NAME,
> T2.COMPANY
> FROM
> (SELECT (U.ID +100) AS NID,
> U.NAME AS NAME
> FROM USERS U) T1
> JOIN
> (SELECT (J.ID +100) AS NID,
> J.COMPANY
> FROM JOBS J) T2 ON T1.NID = T2.NID
> ```
> What I wanted is that T1.NID comes from USER.ID, T1.NAME comes from
> USER.NAME.
>
> Has anyone done similar work? Is there a ready-made example to refer to?
>
>
> Regards!
>
> Aron Tao
>