查询一个数据库并使用结果更新另一个数据库 [英] Querying one database and using the results to update another

问题描述

我正在尝试使用mysql数据库创建存储过程，该存储过程在一个数据库表上查询并使用结果更新另一个数据库表.

我不确定该怎么做.任何建议/解决方案将不胜感激！

这是一段示例代码，可让您大致了解我要执行的操作.

样本代码:

Hi,
I''m trying to create a stored procedure with a mysql Database that queries on one database table and uses the results to update another database table.

I''m not sure how to go about this. Any advice/solutions would be much appreciated!

Here''s a piece of sample code to give you an idea of what I''m attempting to do.

SAMPLE CODE:

DELIMITER //
CREATE PROCEDURE()
BEGIN
SELECT @count := COUNT(col) FROM DB1.TBL1;
UNION
UPDATE DB2.TBL2 SET @count = col;
END//

推荐答案

对于UPDATE语句中的入门者来说，SET部分向后，它应该为SET col = @count，并且您尚未声明@count变量，但是不确定最后一部分在MySql中是否重要.

但是，可以尝试的其他方法是此 [

Well for starters in the UPDATE statement the the SET section is backwards it should be SET col = @count and you haven''t declared the @count variable, not sure if this last part matters in MySql though.

However something else to try is this[^].
Or see if this, which is just from the link, works.

UPDATE DB2.TBL2 a, DB1.TBL1 b
SET a.col= COUNT(b.col)

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