View on GitHub

openEQUELLA

A digital repository providing a single platform to house your teaching and learning, research, media, and library content.

Querying strings

This tutorial continues on from - The basics - primary keys and UUIDs

Virtually all reports will require you to query the text stored in the language_string table.

Despite the fact that this table is designed for storing multiple different text strings for different languages, we will be assuming that there is only going to be a single language specified (for 99.99% of clients this is a safe assumption).

The query

Let’s modify the original “items by modification date” query to include language_string lookups:

SELECT i.id AS item_id, i.uuid, i.version, 
       i_name.text as item_name, be_name.text as collection_name,
       i.date_modified
FROM item i 
INNER JOIN base_entity be on be.id = i.item_definition_id
LEFT JOIN language_string i_name on i.name_id = i_name.bundle_id
LEFT JOIN language_string be_name on be.name_id = be_name.bundle_id
WHERE i.institution_id = CURRENT_INSTITUTION
  AND be.uuid = '20d5d5eb-af16-43b0-a42b-962c57fe87f2'
ORDER BY i.date_modified DESC
LIMIT 10

So each language string lookup requires an LEFT JOIN on the language_string table and a select clause which gets the “text” column.

Here I’ve used the convention “<tablealias>_<column>” for naming of the language_string joins, just to keep some consistency. I’d recommend writing your queries with a naming strategy similar to this.

NOTES
I’ve used LEFT JOIN here instead of INNER JOIN in case there is a null language string, in which case you will still get a row but with a null name.
The item’s name and description are stored in the database, however they are actually generated from the item’s XML and schema definition and aren’t edited directly.