什么是数据库游标？在C#中如何使用游标？

CREATE PROCEDURE ProcessEmployees
AS
BEGIN
    DECLARE @EmployeeID INT
    DECLARE @Name NVARCHAR(50)
<pre class='brush:php;toolbar:false;'>-- 声明游标
DECLARE employee_cursor CURSOR FOR
SELECT EmployeeID, Name FROM Employees WHERE Active = 1

-- 打开游标
OPEN employee_cursor

-- 获取第一行
FETCH NEXT FROM employee_cursor INTO @EmployeeID, @Name

WHILE @@FETCH_STATUS = 0
BEGIN
    -- 在这里处理每一行，比如插入日志
    PRINT 'Processing: ' + @Name

    -- 模拟业务逻辑处理
    -- EXEC UpdateEmployeeStatus @EmployeeID

    -- 获取下一行
    FETCH NEXT FROM employee_cursor INTO @EmployeeID, @Name
END

-- 关闭并释放游标
CLOSE employee_cursor
DEALLOCATE employee_cursor

using (SqlConnection conn = new SqlConnection(connectionString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand("ProcessEmployees", conn))
    {
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.ExecuteNonQuery(); // 执行包含游标的存储过程
    }
}

using (SqlConnection conn = new SqlConnection(connectionString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT EmployeeID, Name FROM Employees", conn))
    using (SqlDataReader reader = cmd.ExecuteReader())
    {
        while (reader.Read())
        {
            int id = reader.GetInt32("EmployeeID");
            string name = reader.GetString("Name");
            // 逐行处理数据
            Console.WriteLine($"ID: {id}, Name: {name}");
        }
    }
}