how to add validation in editable grid if your using multiple updation.

The easiest way to do this is to use the contains() function. This function will return true if any of the values in a list match the provided value, so you can use it to determine if each column value is unique or not. Here's an example:

a!localVariables(
  local!data: {},
  a!gridLayout(
    headerCells: {
      a!gridLayoutHeaderCell(label: "Name"),
      a!gridLayoutHeaderCell(label: "Amount"),
    },
    rows: a!forEach(
      items: local!data,
      expression: a!gridRowLayout(
        contents: {
          a!textField(
            value: fv!item.name,
            saveInto: fv!item.name,
            validations: {
              if(
                contains(remove(local!data.name, fv!index), fv!item.name),
                "This value is a duplicate",
                null
              )
            }
          ),
          a!integerField(
            value: fv!item.name,
            saveInto: fv!item.name
          )
        }
      )
    ),
    addRowLink: a!dynamicLink(
      label: "Add Row",
      value: append(local!data, {name: null, amount: null}),
      saveInto: local!data
    )
  )
)

Thanks for the validation which is helpful ....

Good one..