• The row from which to extract a value is determined by the order in which the rows are organized at the time that the function is executed. 

• If you are working on a randomly generated sample of your dataset, the values that you see for this function might not correspond to the values that are generated on the full dataset during job execution.
  

• If the previous value is missing or null, this function generates a missing value.
• You can use the group and order parameters to define the groups of records and the order of those records to which this function is applied. 
• This function works with the following transforms:
  • Window Transform
  • Set Transform
  • Derive Transform

Output: Returns the value in the row in the myNumber column immediately preceding the current row, when ordered by Date.

For more information on the order and group parameters, see Window Transform.

col_ref

Name of the column whose values are used to extract the value that is k-integer values before the current one.

• Multiple columns and wildcards are not supported.

k_integer

Integer representing the number of rows before the current one from which to extract the value.

• Value must be a positive integer. For negative values, see NEXT Function.
• k=1 represents the immediately preceding row value.
• If k is greater than or equal to the number of values in the column, all values in the generated column are missing. If a group parameter is applied, then this parameter should be no more than the maximum number of rows in the groups.
• If the range provided to the function exceeds the limits of the dataset, then the function generates a null value.
• If the range of the function is valid but includes missing values, the function generates a missing, non-null value.

Example - Examine prior order history