如何随机播种 MySQL 列？

Question

The column in my database contains 4 statuses:

• 0-Active
• 1-Awaiting User input
• 2-Archive In Progress
• 3-Excluded From Archival

I need to go through the column and randomly change things that are not marked as 0 to some random picking of the other 3 statuses.

What would be the best way for me to go about this? It was requested I use a Python script with random seed so that the state could be recreated. Does anyone have thoughts?

Answer 1

I don't really see the point using python here, you can adress the very same requirement with a pure MySQL query, like so:

update mytable set mystatus = floor(1 + rand() * 3) where mystatus <> 0

For each row, expression floor(1 + rand() * 3) gives you a random value between 1 and 3.

As for the seed, the documentation says :

If an integer argument N is specified, it is used as the seed value:

• With a constant initializer argument, the seed is initialized once when the statement is prepared, prior to execution.

• With a nonconstant initializer argument (such as a column name), the seed is initialized with the value for each invocation of RAND() .

One implication of this behavior is that for equal argument values, RAND(N) returns the same value each time, and thus produces a repeatable sequence of column values.