Deal with NULL in Postgres
#Data Warehouse #Postgres #PGSQL
Please deal with null carefully.
SUM
up some values with NULL
in it, we get a value.
WITH base AS (
SELECT
1 AS num
UNION ALL
SELECT
2 AS num
UNION ALL
SELECT
NULL AS num
)
SELECT
SUM(num)
FROM
base
gives us
3
However, if one would add some values up, we get a NULL when one of them is NULL
.
SELECT
NULL + 10 AS null_plus_num
gives us a
NULL
Published:
by Lei Ma;
Authors: Lei Ma
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- til/data/postgres.deal-with-null.md