When installing or upgrading extensions in Joomla!, it may happen that some database table or database column is missed.
To explore if some table or column is missing, run phpMyAdmin on your server and navigate to your database.
Missing table
Check if all tables from the extension (e.g. component) are available - compare list of tables of your database with list of tables of component installation file, e.g. for Phoca Gallery, open:
- com_phocagallery_v4.1.2.zip - unzip it and navigate to: install/sql/mysql/install.utf8.sql - open this file and see the list of tables which should be installed on your site.
Missing column
Click on selected table (mostly when you get database error message, the table which includes an error is listed there) and check the columns of selected table. Compare it with columns in table in installation file which should be installed on your site - the same like for whole table, for example:
- com_phocagallery_v4.1.2.zip - unzip it and navigate to: install/sql/mysql/install.utf8.sql - open this file and see the list of tables. Inside this list you can find the columns which should be installed on your site.
If some table or column is missing, it needs to be installed manually (just run the SQL query which is set in installation file - but be aware, always backup your database before doing some changes there)