You also have the option of using the data tab on the specific table, or use a query without a join.
While I found the data tab doesn't provide me with the combined information and is not optimal for large tables (the "data" table in my DB holds hundreds of thousands of different measurement values and will further grow), yes, there are ways to get the information without a JOIN.
I.e. the following query will provide me with the same information as the JOIN does...
SET @CHANNEL = 3;
SELECT channel_id AS Kanal,(SELECT VALUE FROM `volkszaehler`.`properties`
WHERE `entity_id` = @CHANNEL AND `pkey` = 'title') AS Name,VALUE AS Wert,TIMESTAMP,FROM_UNIXTIME(TIMESTAMP / 1000 ) AS Echtzeit,id AS SQL_ID
WHERE `channel_id` = @CHANNEL and TIMESTAMP> (unix_timestamp(current_timestamp)-24*60*60)*1000
ORDER BY timestamp DESC
However, this brings me back to my original question: In this case also two tables are involved - will a "delete line" on the output delete the affected row from volkszaehler.data only and leave the legend from volkszaehler.properties in place?
Your proposed solution would ... require the user to understand what he's deleting in such cases.
You are right with that. Perhaps a pop-up confirmation message would help? Like "You are about to delete complete line ... from table ... Are you sure?"
Thanks for looking into this!