SQL QUERY replace NULL value in a row with a value from the previous known value

null, sql

Solution

If you are using Sql Server this should work

DECLARE @Table TABLE(
        ID INT,
        Val INT
)

INSERT INTO @Table (ID,Val) SELECT 1, 3
INSERT INTO @Table (ID,Val) SELECT 2, NULL
INSERT INTO @Table (ID,Val) SELECT 3, 5
INSERT INTO @Table (ID,Val) SELECT 4, NULL
INSERT INTO @Table (ID,Val) SELECT 5, NULL
INSERT INTO @Table (ID,Val) SELECT 6, 2


SELECT  *,
        ISNULL(Val, (SELECT TOP 1 Val FROM @Table WHERE ID < t.ID AND Val IS NOT NULL ORDER BY ID DESC))
FROM    @Table t

Problem

I have 2 columns ``` date number ---- ------ 1 3 2 NULL 3 5 4 NULL 5 NULL 6 2 ....... ``` I need to replace the NULL values with new values takes on the value from the last known value in the previous date in the date column eg: date=2 number = 3, date 4 and 5 number = 5 and 5. The NULL values appear randomly.

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