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Is it possible to include a double table in a connection request?

Can I include a DUAL table in a connection request?

Can someone give me an example that includes SYSTIMESTAMPfrom a double table.

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4 answers

One common use (for me) is to use it to create inline views for joining ...

SELECT
  filter.Title,
  book.*
FROM
(
  SELECT 'Red Riding Hood'  AS title FROM dual
  UNION ALL
  SELECT 'Snow White'       AS title FROM dual
)
  AS filter
INNER JOIN
  book
    ON book.title = filter.title

[This is a deliberately trivial example.]

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In principle, you can, but there is no need.
you can add the systimestamp column alias to any query that you already have:

SELECT t.col1, t.col2, systimestamp
FROM your_table t

Will give the same results as

SELECT t.col1, t.col2, d.st
FROM your_table t, (select systimestamp st from dual) d

, , .

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Try this solution:

 select (select SYSTIMESTAMP from dual ) as d
        /*
           Here you can add more columns from table tab
        */ 
 from tab
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There should be no need, the keyword DUALis a way of saying that you are not querying the table, if you want to “join” DUALto another table, just go to another table, including your columns that are not in the table in the select clause.

EDIT: As the comments say, this statement is false - this is a table. DUAL

I still think it makes no sense to include (with a question)

DUAL table in join

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