I have a connection to the database and run an sql script to retrieve data from it.
Now I need to update the sql script everytime. therefor I like to put an variable in the sql script and just have to change the input of the variable to run the script again.
these two nodes I have: “Database Connector” and “Database reader”
In “Database Reader” I have the next sql statement:
select p.barcode
,strack.tiny_01(w.id) as Dest_to_Source
from strack.vsk_wells w
inner join strack.vsk_plates p
on p.id = w.pte_id
where p.barcode = ‘19GROF059’
order by w.row_number,w.column_number.
Now I like to have ‘19GROF059’ as a variable and use another node for input of the variable and then run the sql with the new input value
Hi,
Ok let’s imagine you have something in columns of a table and it contains ‘19GROF059’, ‘19GROF058’, ‘19GROF057’, etc…
You want to use each value to make sql queries. You can use for looping your values
1 - a chunk or a group loop start / end.
2 - Inside the loop a table row to variable
3 - then transform the variable in a query via string manipulation (variable version) (can be sometimes a bit tricky don’t forget the escape character /)
5 - In your database reader you can go in the window “Flow variable” and attribute the “sql_statement” to the value of your variable (the one that contains your query as a variable value in the output port of the string manipulation variable version).
6 - launch your loop.
If you try to do a first knime workflow version explaining where you are stuck. It could be easier to answer more precisely.