ExecuteNonQuery returning -1 when using sql COUNT despite the query string

问题

For some reason, ExecuteNonQuery() in C# returns -1, though when I run a query separately, the value returns the actual value needed.

For Example:

try
{

    var connString =\"Data Source=ServerName;InitialCatalog=DatabaseName;Integrated Security=true;\"
    SqlConnection conn = new SqlConnection(connString);

    SqlCommand someCmd = new SqlCommand(\"SELECT COUNT(*) FROM SomeTable\");

    someCmd.Connection = conn;

    conn.Open();

    var theCount = cmd.ExecuteNonQuery();

    conn.Close();
}
catch(Exception ex)
{
    Console.WriteLine(ex.Message);
}

When the command is executed it returns -1. Though if run the query separately,

SELECT COUNT(*) FROM SomeTable;

Column returns one row with a count of 4 if that table being queried has 4 rows.

回答1:

Based on MSDN:

For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command. When a trigger exists on a table being inserted or updated, the return value includes the number of rows affected by both the insert or update operation and the number of rows affected by the trigger or triggers. For all other types of statements, the return value is -1. If a rollback occurs, the return value is also -1.

You want to return the number of rows affected by the command and save it to an int variable but since the type of statement is select so it returns -1.

Solution: If you want to get the number of rows affected by the SELECT command and save it to an int variable you can use ExecuteScalar.

var theCount = (int)cmd.ExecuteScalar();

回答2:

You can use Ef core with Ado.net like this example

var context = new SampleDbContext();
using (var connection = context.Database.GetDbConnection())
{
    connection.Open();

    using (var command = connection.CreateCommand())
    {
        command.CommandText = "SELECT COUNT(*) FROM SomeTable";
        var result = command.ExecuteScalar().ToString();
    }
}

来源：https://stackoverflow.com/questions/38060489/executenonquery-returning-1-when-using-sql-count-despite-the-query-string

标签

sql

sql-server

ado.net

executenonquery