title: Is xlock,rowlock,holdlock correct?
body: <p>I saw the combination of (xlock,rowlock,holdlock) is used for a table. Refer to online book, holdlock is to hold shared lock(for read,such as select) until transaction is done and xlock is exclusive lock(write lock) for data modification, such as update, insert or delete. How could we use read and write a table at the same time? I am wondering if the combination take effect or not. Confusing... </p>