The number of table features is printed on its header.
Selecting
Sorting
Searching
Field Calculator
Selecting
Rows can be selected by clicking on the row number on the left side of the row. Selecting a row doesn't change the current cursor position. Multiple rows can be marked by holding the key.
A continuous selection can be made by holding the key and clicking on several row headers on the left side of the rows. All rows between the current cursor position and the clicked row are selected.
Sorting
Each column can be sorted by clicking on its column header. A small arrow indicates the sort order (downward pointing means descending values from the top row down, upward pointing means ascending values from the top row down).
Use button to sort selected rows and display them in first table rows. To show selected records only, use the check box .
Searching
For a simple search by attributes on only one column the field can be used. Select the field (column) from which the search should be performed from the drop down menu and hit the button.
For more complex searches use the . This button opens the Query Builder and allows you to select table features matching a SQL-like WHERE clause.
Field Calculator
The button in the attribute table allows to perform calculations on basis of existing attribute values or defined functions, e.g. to calculate length or area of geometry features.
The results can be written to a new attribute column or it can be used to update values in an already existing column.
You have to bring the vector layer in editing mode, before you can click on the icon to open the dialog.