将特定的随机值插入临时表

Question

I need to create some dummy data for one of the new tables in our database. I will be getting values from existing tables and also will be creating new columns in which values are randomly chosen from a list of values.

My table structure:

ID -- increment by 1
PersonsID -- will get this values from a different table
Status --Need to insert random values of example "Waived" or "Enrolled"
StatusDate -- need to insert random DateTime within past few months
School --Need to insert random values of example "A", "B", "C", "D"
ChangedBy --Need to insert random username from a different table

Can someone guide me regarding how to insert random, but specific values in a table?

Answer 1

You will need different techniques for different types of randomized values

For example, to get random datetime within past 90 days.

select dateadd(second, -90*86400*rand(), getdate()) -- 86400 seconds in a day

To select 'A','B','C', or 'D'

select substring('ABCD', convert(int,rand()*4+1), 1)

To select an arbitrary value (StateCode) from a table (USStates)

select top 1 StateCode from USStates order by newid()

Then you combine these techniques to insert the data your need

Answer 2

If you want to get random values, the basic expression in SQL is rand(checksum(newid())) . Here are ways you might use this.

For the id , I will assume you have a new table with an identity column. Here is an example query:

insert into newtable(PersonsID, status, StatusDate, School, ChangedBy)
    select PersonsId,
           (case when rand(checksum(newid())) < 0.5 then 'Waived' else 'Enrolled' end),
           cast(getdate() - 90 * rand(checksum(newid()))),
           (select top 1 col
            from (select 'A' as col union all select 'B' union all select 'C' union all select 'D'
                 ) t
            order by rand(checksum(newid())) 
           ) ,
           (select top 1 username
            from othertable ot
            order by rand(checksum(newid())) 
           )
    from Persons;