prevent same date duplicate name insert

[Amyosaka]

Some one please tell me how to prevent same person input his name more than once on the same date?

My app has three item: Date/time, Name, Item

For the Name I want to add a condition(valid if) to prevent people to input his name twice on the same day.

Thank you 

[Suvrutt_Gurjar · Accepted solution]

Please create a virtual column or real column (if the user updates date time and name through a form) called say [NamenDate] with an expression something like 

CONCATENATE( [Date/Time], "-",[Name]) 

Then, in the valid_if  of the [Name] or [Date/Time] column, you can have an expression , something like 

ISBLANK(
FILTER(
"Table Name",
([_THISROW].[NamenDate] = [NamenDate])
)
- LIST([_THISROW])
)

Please replace 'Table Name" with the actual table name you have.

The technique to avoid duplicates is mentioned in the article below in the last section.

List expressions - AppSheet Help

[Amyosaka]

@Suvrutt_Gurjar sorry but I have another question now. the person who ordered lunch at 7am for today may want to order again at 8am for another day:s lunch, so the same Name may appear many times, if I use FILTER, the App will not allow the same name apear again right?

[Suvrutt_Gurjar]

Could you elaborate what type of filter you are referring to and for what purpose?

[Amyosaka]

Hi @Suvrutt_Gurjar , I want to make my App as simple as possible , so I thought out a way to make it like this:

①App top(edited):

③spreadsheet(edited) :

③-EnumList:

From the 2nd photo you can see if I input exactly the same data like cell D2 the App will stop me says it is duplicated, but if I just input 2023/01/21 or 2023/01/21,2023/01/25 the App still accepted it as new order. Is there a way to solve this problem?

[Amyosaka]

Thank you very much!!