CODEWITHSUNDEEP
databaseknime
Uma Ramya
Uma Ramya

Reputation: 11

Database query node in knime

I was Struggling with the node "Database Query".
It shows the default Query as "SELECT * FROM #table# "

While entering the query it shows the error as "Invalid Settings" Database view place holder #table# must not be replaced.

What actually #table# represent?

How does the Database Query node execute?

Can anyone repond, please.

Upvotes: 0

Views: 2139

Answers (1)

SteveR
SteveR

Reputation: 613

#table# represents the table in the incoming database connection port. The node wraps this incoming connection as a sub query, so for example if you have a connection to a table called 'Names' with a column 'Surname', a column 'Forename' and a column 'Age', and you have previously used a database row filter node to filter by Surname='Smith' then the incoming connection will look something like:

SELECT * FROM (SELECT * FROM Names) table_1234567890 WHERE "Surname"='Smith'

If you want to then use the Database Query Node to search for all people John Smith, aged 30 - 45, then in the node dialog you set

SELECT * FROM #table# WHERE Forename='John' AND Age BETWEEN 30 AND 45

Now, if you look at the output port, on the 'Connection' tab, the SQL will look something like:

SELECT * FROM (SELECT * FROM (SELECT * FROM Names) table_1234567890 WHERE "Surname"='Smith') WHERE Forename='John' AND Age BETWEEN 30 AND 45

Upvotes: 2

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