Vadivel's blog

One of the common problem the database developers face in their day to day life is record concurrency issues. Lets try to address that with the help of timestamp data type. Lets assume that Sarah and Ram are reading a same record. First Ram updates that record with some new data. Later if Sarah also updates the record (mind you she is viewing the old content only still) then it would overwrite the changes made by Ram. There are two ways of solving this issue they are: 1. Pessimistic Locking 2. Optimistic Locking Pessimistic Locking: First person who reads the record would put a lock on it so that nobody else can change it until he is done with it. Only when he releases the record the other user can make use of it. This method is not recommended because it might also takes hours or days together for the first person to release his lock due to various reasons. Optimistic Locking: The record would be locked only when a user wants to modify its content. SQL Server has a TSEqual (I presum...

As much as possible it is advisable to keep large text in a document on the file system and store a link to that within the database. Why do I say this? Because for storing large chunk of data we need to depend on the TEXT, NTEXT and IMAGE data types. So What? There are 2 disadvantages in it. They are: 1. These data types does not support commonly used string functions such as Len, Left, Right etc., 2. It occupies more / large space in the DB which internally means there might be a performance issues if you store such data in the database. Inspite of all these if you still want to use TEXT data type due to your business requirment then these functions might interest you! 1. PatIndex() 2. TextPtr() 3. ReadText() 4. TextValid() PatIndex() This function is useful with TEXT, CHAR and VARCHAR data types. This seeks for the first occurrence of a pattern within a string. If the pattern is found, it returns the character number where the first occurrence of the pattern begins. For better under...