Categories:: Data metric functions

NULL_KEYWORD_PERCENT (system data metric function)¶

Returns the percentage of column values that are a text placeholder for a missing value, such as 'null' or 'n/a', rather than a SQL NULL. The percentage is computed over the total row count, including NULL values in the denominator.

This topic provides the syntax for calling the function directly. To learn how to associate the function with a table or view so it runs at regular intervals, see Associate a DMF.

Syntax¶

SNOWFLAKE.CORE.NULL_KEYWORD_PERCENT(<query>)

Arguments¶

query: Specifies a SQL query that projects a single column.

Allowed data types¶

The column projected by the query must have the VARCHAR data type.

Returns¶

The function returns a FLOAT value. The function returns NULL if the table or view has no rows.

Usage notes¶

The function counts the values none, null, nil, nothing, and n/a. Matching is case-insensitive and ignores leading and trailing whitespace, including no-break spaces.
SQL NULL values, empty strings, and other placeholders such as na or - are not counted. To count SQL NULL values, use NULL_PERCENT.

Example¶

Measure the percentage of text placeholders for missing values in the middle_name column:

SELECT SNOWFLAKE.CORE.NULL_KEYWORD_PERCENT(
  SELECT
    middle_name
  FROM hr.tables.employees
);