cw_td_nvp.sqlx

config { hasOutput: true }
/*
 * Copyright 2022 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* Similar to teradata NVP function - extract a value from a key-value separated string */
CREATE OR REPLACE FUNCTION ${self()}(haystack STRING, needle STRING, pairsep STRING, valuesep STRING, occurence INT64) RETURNS STRING 
OPTIONS (
    description="Similar to teradata NVP function - extract a value from a key-value separated string"
)
AS (
   NULLIF(ARRAY(SELECT ARRAY_TO_STRING((select ARRAY_AGG(v) from UNNEST(kv) v WITH OFFSET o WHERE o > 0), valuesep) FROM (
        SELECT SPLIT(pairs, valuesep) AS kv, o FROM UNNEST(SPLIT(haystack, pairsep)) AS pairs WITH OFFSET o
   ) t WHERE kv[SAFE_OFFSET(0)] = needle ORDER BY o ASC)[SAFE_ORDINAL(occurence)], '')
);