Evaluates a provided query parameter and returns its value as TEXT.

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Syntax

PARAM(<parameter>)
ParameterDescriptionSupported input types
<parameter>Constant string containing the name of the query parameter to evaluate.TEXT

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Return Type

TEXT

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Specifying query parameters

To use the PARAM function, you need to define query parameters using the SET query_parameters command. The function relies on a request property named query_parameters in JSON format. Use the following schema: 
query_parameters: json_array | json_object
json_array: [ json_object, … ]
json_object: { "name" : parameter_name, "value" : parameter_value }
You can include a single query parameter in the request properties, for example: 
{ "name": "country", "value": "USA" }
or multiple query parameters: 
[ 
  { "name": "country", "value": "USA" },
  { "name": "states", "value": "WA, OR, CA" },
  { "name": "max_sales", "value": 10000 }
]

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Example

The following example shows how to use a Common Table Expression (CTE), through a WITH clause, to generate input data and apply a query parameter in a computation. The WITH clause defines a temporary dataset, and the query evaluates whether each row matches the parameter value using PARAM. 
SET query_parameters = [{ "name": "track_name", "value": "Nürburgring" }];

WITH fastest_laps(name, difficulty, fastest_lap, driver) AS (
  SELECT 'Monaco', 'Hard', '1:10.166', 'Lewis Hamilton'
  UNION ALL
  SELECT 'Silverstone', 'Medium', '1:27.097', 'Max Verstappen'
  UNION ALL
  SELECT 'Nürburgring', 'Easy', '1:29.468', 'Valtteri Bottas'
)
SELECT *
FROM fastest_laps
WHERE name = PARAM('track_name');
Returns
namedifficultyfastest_lapdriver
NürburgringEasy1:29.468Valtteri Bottas