Find one algorithm: quickly change the value of a row in the data table.

tsh6969

Known a row, the keywords are DDNO, SEHAO, CHICUN need to determine whether the original record of the row exists in a memory table, if there is a change, if not, add. It is too slow to use the loop directly. Please enlighten me on an excellent algorithm!

psycholmu

Memory table?

If it is from the database, you can directly use select count (*) from XXX where ............
Then see if the number of rows is 0

If the data is generated during the running of the program, you can consider using hashtable to store and then directly use the key value to match

wudi1982

Stored procedure

tsh6969

The meaning may not be made clear, and the DATASET is now used to operate. Suppose there is a data set ds, there is a table A in ds, there is a row record dr, and the primary key column is a combination of 3 columns "DDNO, SEHAO, CHICUN". Now I want to determine whether dr exists in table A based on the primary key, and update Starting value, if not, add new row to table A

tsh6969

Because there are too many records in table A, I feel that using the select method and view filtering, or the loop is very slow.

psycholmu

Create DataView to filter data by RowFilter

丢丢猫

DataRows [] rows = ds.table [0] .select ("DDNO = 'A' and SEHAO = 'B' and CHICUN = 'C'");
if (rows.length = 1)
{
    Write your logic here
}

tsh6969

Upstairs, of course, I tried the method you mentioned, and the speed is still not ideal. If you only need to quickly get the value of a certain column and a certain column according to certain conditions, the algorithm should be simpler. How to write such an algorithm?