Re: creating view - conditional testing in construct - Mailing list pgsql-novice
From | Mohlomi Moloi |
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Subject | Re: creating view - conditional testing in construct |
Date | |
Msg-id | L6792DBB82522448282AB7FBDAA3C68D3.1256298790.scalix.khulisa.com@MHS Whole thread Raw |
In response to | Re: creating view - conditional testing in construct (Nathaniel Trellice <naptrel@yahoo.co.uk>) |
Responses |
Re: creating view - conditional testing in construct
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List | pgsql-novice |
Alternatively you can use COALESCE in your concatenation, this way even NULL/empty fields are catered and will be part of summary. Regards, Hlomiza -----Original Message----- From: Nathaniel Trellice [mailto:naptrel@yahoo.co.uk] Sent: 23 October 2009 13:43 To: rterry@pacific.net.au; pgsql-novice@postgresql.org Subject: Re: [NOVICE] creating view - conditional testing in construct Hi Richard, The simplest way that I can think of to do it would be to use a conditional expression in the creation of your view. The 'CASE' expression would fit the bill (see section 9.16.1 of the 8.4.1 manual). Slightly altering your conventions for clarity you might do it like this: CREATE vwMyView VIEW AS vworganisationsemployees.fk_organisation, vworganisationsemployees.fk_branch, [a bunch more columns] -- start of summary (vworganisationsemployees.title || ' ' || vworganisationsemployees.firstname || ' ' || vworganisationsemployees.surname [a bunch more concatenated summary fields] || (CASE WHEN vworganisationsemployees.fk_address IS NULL THEN '' ELSE (vworganisationsemployees.fk_street || ' ' || vworganisationsemployees.fk_suburb) END) ) AS summary -- end of summary There are more elegant ways using stored procedures to do this kind of thing (especially the string concatenation with a comma and/or a space between the fields--you can add the field delimiter only if the next field is non-NULL/empty and only if you've already had a non-NULLempty entry), but this should get you going. Nathaniel ----- Original Message ---- From: richard terry <rterry@pacific.net.au> To: pgsql-novice@postgresql.org Sent: Fri, 23 October, 2009 0:21:35 Subject: [NOVICE] creating view - conditional testing in construct Hi all, I'm struggling to find the syntax to create a view in this situation. I'm joining a table to an existing view create vwMyView as vworganisationsemployees.fk_organisation, vworganisationsemployees.fk_branch, vworganisationsemployees.fk_employee, vworganisationsemployees.fk_person, vworganisationsemployees.fk_address, ** I want all these fields to end up as as field called, say summary (vworganisationsemployees.title ||' '::text) || (vworganisationsemployees.firstname ||' '::text) || (vworganisationsemployees.surname ||'( '::text) || (vworganisationsemployees.occupation ||') '::text) || (vworganisationsemployees.organisation ||' '::text) || (vworganisationsemployees.branch ||' '::text) as summary so far so good, as all the employees of the organisations will always contain the data, however in the vwOrganisationsEmployees, some rows will not contain the address of the branch ie fk_address is null, and the street and suburb fields are null. So at this point in the query it works ok, but I want also to add the address of the branch into the summary field, and in some records there is no fk_address and hence no street or suburb. so I want to be able to conditionally test if fk_address is null, if it is, then keep adding the street, suburb, postcode to the field which ends up being called summary. Any help appreciated. Regards Richard -- Sent via pgsql-novice mailing list (pgsql-novice@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-novice -- Sent via pgsql-novice mailing list (pgsql-novice@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-novice
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