Question

我有使用table1进行此查询

SELECT DATE_FORMAT(FROM_UNIXTIME(t.TSTAMP), "%Y-%m") AS "timePeriod", COUNT(*) AS "prod1"

使用col'timePeriod'和col'prod1'给出了完美的2列结果。我现在想更新table2.prod1，其中主键是'timePeriod'。

我试过

Answer 1

这样的东西......我无法测试它。

UPDATE table2 AS T2
INNER JOIN
(
    SELECT DATE_FORMAT(FROM_UNIXTIME(TSTAMP), "%Y-%m") AS "timePeriod",
    COUNT(*) AS prod1 FROM table1
    GROUP BY DATE_FORMAT(FROM_UNIXTIME(TSTAMP), "%Y-%m")
) AS T1 USING (timePeriod)
SET T2.prod1 = T1.prod1;

Answer 2

这将按照您指定的方式执行

INSERT 
IGNORE // include this if you want conflicts to be ignored
INTO table2 (
    timePeriod,
    prod1
)
SELECT 
    DATE_FORMAT(FROM_UNIXTIME(t.TSTAMP), "%Y-%m"),
    COUNT(*)

// you didn't include a "FROM" so added relevant place here
FROM table1 

// Include this if you want conflicts to append to the existing row
ON DUPLICATE KEY UPDATE prod1 = prod1 + VALUES(prod1) 

// Include this if you want conflicts to replace the existing row
ON DUPLICATE KEY UPDATE prod1 = VALUES(prod1)

在一个table1中按月计算（Unix时间戳）并将结果写入表2

2 个答案: