Updating Attribute Data

Browser Window:

QGIS Browser Window

Buttons on the bottom from left to right are:-

• Unselect All
  
• Move Selection to Top
  
• Invert Selection
  
• Copy Selected Rows to Clipboard
  
• Zoom Map to the Selected Rows
  
• Pan Map to the Selected Rows
  
• Toggle Editing
  
• Save Edits
  
• Delete Selected Features (rows)
  
• New Column
  
• Delete Column
  
• Open Field Calculator
  
• Look For (enter search terms) in (use the pull down to select the column to search)
  

The attribute table has several duplicate rows. To delete them

1. Press the Toggle Editing to begin an Edit Session
   
2. Press the Delete Columns button
   
3. Select the column(s) and press OK
   

To add new columns:

1. Press the New Column button
   
2. Enter the details for the new column
   

Add column dialog

Update Columns with the Field Calculator

I want to update the three new columns I’ve added. To update columns:

1. Right click on the layer in the Layer Panel
   
2. Select View Attribute Table
   
3. Press the Toggle Editing button to begin an Edit Session
   
4. Press the Field Calculator
   

QGIS Field Calculator

1. Select to either create a new field or to update an existing field. If you’re updating an existing field then use the pull down to select the field
   
2. Complete the Expression builder by either double clicking functions or typing the expression.
   
3. Functions include:
   

• Operators e.g.+-*/ etc
  
• Maths e.g. cos, sin etc
  
• Conversions e.g. to integer, to string, to decimal
  
• Geometry e.g. feature’s length, area, perimeter, x, y
  
• Record – Row number or ID
  
• Fields and Values