How to find duplicates in a mariaDB tabel

Question

Hi,

I have a database on the net and consist of 2 tabels i.e. Naam of the employee and his number.

number naam

1000 Rinaldo

1001 Other

how can i add a name and number without getting uplicates. I've found som on the net with google and is Linq what i do not get. Example in LINQ c# Please guide me to the process.

            var group = dt.AsEnumerable().GroupBy(row => row.Field<string>("Personeel")).Select(g => new
            {
                group = g.Key,
                first = g.Max(row => int.Parse(row.Field<string>("Naam"))).ToString(),
                second = g.Max(row => row.Field<int?>("PersoneelsNummer") ?? 0)
            }).ToList();

other I have tryed:

            var group = dt.AsEnumerable().GroupBy(row => row.Field<string>("Personeel")).Select(g => new
            {
                group = g.Key,
                first = g.Max(row => int.Parse(row.Field<string>("Naam"))).ToString(),
                second = g.Max(row => row.Field<int?>("PersoneelsNummer") ?? 0)
            }).ToList();

Al coming from StackOverflow

https://stackoverflow.com/questions/58835299/find-duplicates-in-a-datatable-then-compare-duplicates

Answer 1

You should create a unique index in the table to disallow the duplication:

create unique index on myTable (number, naam);

This way you cannot enter duplicates. Reference: CREATE INDEX