SQL Server Locks Question:
Explain isolation levels that SQL server supports?
Answer:
SQL Server isolation levels:
READ COMMITTED: Shared locks are held while any data is being read.
READ UNCOMMITTED: Specifies isolation level 0 locking. There are thus no shared locks or exclusive locks. It is the least restrictive of all the isolation levels.
REPEATABLE READ: Locks are applied on all data being used by a query. However, new phantom rows can be inserted into the data set by another user and are included in later reads within the current transaction.
SERIALIZABLE: Issues a range lock on data set, preventing other users to update or insert data into dataset until the transaction is complete.
READ COMMITTED: Shared locks are held while any data is being read.
READ UNCOMMITTED: Specifies isolation level 0 locking. There are thus no shared locks or exclusive locks. It is the least restrictive of all the isolation levels.
REPEATABLE READ: Locks are applied on all data being used by a query. However, new phantom rows can be inserted into the data set by another user and are included in later reads within the current transaction.
SERIALIZABLE: Issues a range lock on data set, preventing other users to update or insert data into dataset until the transaction is complete.
| Previous Question | Next Question |
| Do you know the isolation level that SQL Server support? | Do you know what are the differences between lost updates and uncommitted dependencies? |