Four basic operations of ado.net

Executescaler: Read-Only. Read the first column of the First row in the returned result set.
Executenonquery: Write-only, suitable for situations where only modification is needed
Executereader: Read-only, can read multiple rows
Dataadapter/Dataset: After Reading data, you can perform offline operations, and then update the changes back to the data. This function is equivalent to a database with support for relation, constraint, view, sort, and search, and can be directly connected.. Net Control binding is equivalent to a business layer function and can be transmitted to other remote machines through WebService, which is very convenient.