Help pages for DBview

• Start Screen
• Queries
• Parameters
• SAMP connection

Start screen

To personalize the DBViewer, a new user should first log in with his or her username. Optionally, a user can click a project if wanted (log-in + project: see top row). After these steps the user can click one of the table categories listed on the start sceen (but also present at the top right). Each category consists of a list of tables, with each table having, if available, a link to a table description. After clicking a table, the user is shown a query screen with lots of attributes to be queried.

Query Page

The query page consists of a tree view of the current class and all its dependencies and attributes. The dependencies can be unfolded, the attributes can be used to query on. If a dependency is unfolded when the submit button is clicked the output will contain the attributes of this dependency. There are three different kinds of attributes to query on :

• Dates; a date can be given as yyyy-mm-dd, yyyy-mm-dd hh:mm:ss or yyyy-mm-dd hh:mm:ss.ff, so date only, date and time (without fractional seconds), date and time with fractional seconds
• Numbers; integers like 1, 100 and floats like 3.4, 123.45
• Strings; querying on strings is case insensitive, see the operator like for wildcards

The following operators are supported, although not every attribute type supports all of them :

• <; The less then operator
• >; The greater then operator
• =; The is equal to operator
• !=; The is not equal to operator
• like; The like operator is used to compare strings, use % as a wildcard for zero or multiple characters, use _ as a wildcard for a single character. For example filling in like RUBIN% matches strings as Rubin, RUBIN123, rubinobservatory.
• not like; The not like operator
• between; The between operator queries for results between the given values, specify as : value1,value2
• not between; The inverse of the between operator, specify as : value1,value2
• contains (=); List attribute contains exaclty given value, use comma separation for multiple values
• not contains (=); The inverse of contains (=)
• contains (like); List attribute contains given pattern (see like), not possible to give multiple values
• not contains (like); The inverse of contains (like)

Parameters

There are two sets of parameters: general parameters and local parameters. The general parameters can be accessed from the top row under 'preferences'. The local parameters are always located above the query page. Below is a description of all parameters. Suggestions for additional parameters are welcome! Please use the contact page (see top row).

• expand_descs: Expand the result for desc_list_property. Each entry in a desc_list_property is shown on separate row.
• export options:
  • Comma separated values: Table-output as comma-separated-values.
  • pickle-d lists: exports table as list of lists in python-format to be read by Unpickler routine.
  • HTML (Default): output is shown in browser.
  • Links to download all files: A text file is returned containing links to all FITS files present in the displayed table.
  • SQL statement: SQL query as text-file.
  • VOTable XML: XML VOTable format, compatible with current VO programs.
  • FITS: write table in fits format.
• fcontext_project_only: YES (default): only data belonging to the set project is visible.
• hide_columns: YES (default): Hide the less interesting columns, these columns contain mostly default values for all objects.
• hide_context_attrs: Hide the context attributes in the object view (and class query form)
• numrows: This specifies the number of rows visible on the output page, where numrow means unlimited. Note, in the browser the upper limit to be shown is 1000, for the other export options an ulimited amount of rows can be written to the output.
• show_comments: Show a link to the Comments per object in the result table.
• show_empty_joins: When expanding attributes is selected not all atribute instances will expand (or joined), should these be showed.
• show_expanded: NO (Default); YES: all attributes in expanded leafs will be shown in the DBViewer result page, this can be very slow or could even crash when a user requests very deep and/or large trees.
• SQLbox_height: This number specifies the height of the SQL box containing the SQL (see bottom query-output page).
• SQLbox_width: This number specifies the width of the SQL box containing the SQL (see bottom query-output page).
• use_checkboxes: NO (default): YES: checkboxes can be used to select rows; Manual SQL is not possible anymore when selecting this option.

SAMP connection

The result of a DbView query can be send to another (VO) application via SAMP. For example topcat can be used, the advantage of topcat is that it comes with a SAMP hub. A SAMP hub must be running, otherwise the connection can not be made.

Click on the "Send via SAMP" button to send the current result to other SAMP enabled applications. When sending via SAMP it is not the data that is send, but the URL of the data. The receiving application will open the URL and interpret the result as a VO table.

If the SAMP connection does not work please try the following:

• On the command line try connecting to the SAMP hub "curl http://localhost:21012/", that should give back HTML about the XML-RPC server (hub) running. If you get "Connection refused" then the hub is not running and sending via SAMP will not work.
• Try to ping the SAMP hub Ping SAMP, if that gives True then the hub can be pinged, otherwise not and probably the hub is not running.