Categories:: Data metric functions

NULL_PERCENT (system data metric function)¶

Returns the percentage of columns values that are NULL for the specified column in a table.

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 to automate data quality checks.

Syntax¶

SNOWFLAKE.CORE.NULL_PERCENT(<query>)

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Arguments¶

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

Allowed data types¶

The column projected by the query must have one of the following data types:

DATE
FLOAT
NUMBER
TIMESTAMP_LTZ
TIMESTAMP_NTZ
TIMESTAMP_TZ
VARCHAR

Returns¶

The function returns a NUMBER value.

Example¶

Measure the percent of NULL values for the SSN column (i.e. US social security number):

SELECT SNOWFLAKE.CORE.NULL_PERCENT(
  SELECT
    ssn
  FROM hr.tables.empl_info
);

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+----------------------------------------------------------------+
| SNOWFLAKE.CORE.NULL_COUNT(SELECT ssn FROM hr.tables.empl_info) |
+----------------------------------------------------------------+
| 1                                                              |
+----------------------------------------------------------------+