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CREATE TABLE tab AS
SELECT '0000-00-00 00:00:00' AS time, 'GOOGLE' AS company, 40 AS quote
UNION SELECT '2012-07-02 21:28:05' , 'GOOGLE' , 60
UNION SELECT '2012-07-02 21:28:51' , 'SAP' , 60
UNION SELECT '2012-07-02 21:29:05', 'SAP' , 20
Records: 4 Duplicates: 0 Warnings: 0
SELECT
company,
quote,
LAG(quote) OVER(PARTITION BY company ORDER BY time) AS prev_quote
FROM tab
| company | quote | prev_quote |
|---|---|---|
| 40 | null | |
| 60 | 40 | |
| SAP | 60 | null |
| SAP | 20 | 60 |