在Postgresql 8.4中，您可以使用窗口函数LAG访问上一行并进行比较，以查看其是否具有“ from”和“ to”相同的值：
SELECT "from", "to", timestamp
FROM
(
SELECT
"from",
"to",
timestamp,
LAG(("from", "to")) OVER (ORDER BY timestamp) AS prev
FROM Table1
) T1
WHERE ("from", "to") IS DISTINCT FROM prev
结果：
from to timestamp
1 2 0000
1 3 0003
1 2 0005
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