How to join different VizieR tables in the web vizier application.
Example:
The Tycho catalogue contain 2 tables I/239/hip_main and
I/239/tyc_main, and we wish to display
the following fields:
The result combines the two tables I/239/main and I/239/tyc_main, and each line gives data from both tables for the same Hipparcos number.
In relational terminology it means making an extern or outer join. We will make a join and print all rows of a given table even if there is no corresponding row in the second table.
Then click on the Submit button
If you execute the same query without setting the outer join (radio button not checked), the query returns only the rows with a HIP number present in both tables.
You can set one, two or more joins on two or more tables. You are just limited to one outer join (see radio button on fig Help_img) if you want to display rows even if there is no connection with the other tables.
If you want make a join, you can specify it in the table selection step: for this purpose, click on the join selected tables button. You can still select a join at the last step (see figure Help_img) by clicking on the fields image or (join link).
After selecting a field for a join, you will see some colored lines which confirm that you will make a join. The third column lists some information about the role of the field:
When you have selected more than 2 tables, it is possible to make a join on a field which does not exist in one of the tables. In that case, the query result consists in the cartesian product between the table which lacks the field and the result of the join query between the other tables. If this happens, a warning message appears, located on the first colored lines,
There are some restrictions about this second (unsecure) join:
Example:
In the Hipparcos/Tycho catalogue with tables
I/239/hip_main and I/239/tyc_main:
Special notes about coordinate fields:
we draw attention on a join query using a coordinate field. In that case
the query will connect only data which have exactly the same value
(value understood as a string).
This sort of join does not use a cone search method:
therefore, two tables which
contain the same object but with slightly different coordinates will
give an empty result.
Examples:
last update: ls: cannot access '0.htx': Operation not permitted ls: cannot access '1.htx': Operation not permitted ls: cannot access '1g.htx': Operation not permitted ls: cannot access '2.htx': Operation not permitted ls: cannot access '3.htx': Operation not permitted ls: cannot access '4.htx': Operation not permitted ls: cannot access '5.htx': Operation not permitted ls: cannot access 'DirSearch.htx': Operation not permitted ls: cannot access 'ac2000.htx': Operation not permitted ls: cannot access 'adapt.htx': Operation not permitted ls: cannot access 'args.htx': Operation not permitted ls: cannot access 'batchmode.htx': Operation not permitted ls: cannot access 'colors.htx': Operation not permitted ls: cannot access 'cst.htx': Operation not permitted ls: cannot access 'customcol.htx': Operation not permitted ls: cannot access 'customcol1.htx': Operation not permitted ls: cannot access 'f_bgcat.htx': Operation not permitted ls: cannot access 'f_bgdat.htx': Operation not permitted ls: cannot access 'f_bgtit.htx': Operation not permitted ls: cannot access 'f_goviz.htx': Operation not permitted ls: cannot access 'f_script.htx': Operation not permitted ls: cannot access 'faq.htx': Operation not permitted ls: cannot access 'file.htx': Operation not permitted ls: cannot access 'footprint.htx': Operation not permitted ls: cannot access 'gsc.intro.htx': Operation not permitted ls: cannot access 'gsc1.2.intro.htx': Operation not permitted ls: cannot access 'gsc1.3.intro.htx': Operation not permitted ls: cannot access 'head.htx': Operation not permitted ls: cannot access 'history.htx': Operation not permitted ls: cannot access 'index.htx': Operation not permitted ls: cannot access 'intro.htx': Operation not permitted ls: cannot access 'menu.htx': Operation not permitted ls: cannot access 'navbar.htx': Operation not permitted ls: cannot access 'output.htx': Operation not permitted ls: cannot access 'query_setup.htx': Operation not permitted ls: cannot access 'syntax.htx': Operation not permitted ls: cannot access 'tail.htx': Operation not permitted ls: cannot access 'ucd_example.htx': Operation not permitted ls: cannot access 'vizjoin.htx': Operation not permitted ls: cannot access 'xy.htx': Operation not permitted