If you are searching to find info regarding Not Null Constraint so that you can remove the not null constrain using sql, it is more than likely you will find help only on adding Not Null constraint to a oracle table, but if you want to remove the constraint, this will help :-)
The syntax to remove the null constraint from an oracle table is
ALTER TABLE < table name > MODIFY <column1 > NULL;
The syntax to add the constraing is (you will find everywhere) :
ALTER TABLE <table name > MODIFY <column1 >NOT NULL;
For other databases: Set Null/set not Null
To delete a multimedia column from Oracle database
Set the column to empty_blob() / empty_clob()
But there is a catch read more Deleting BLOB value from the database
Google's solution -- looking at a page's "link popularity" -- isn't applicable to most corporate search environments. However, enterprises have access to plenty of other extratextual information. Documents can be tagged by date, author, subject and, above all, intended audience and purpose. Customer communications can be associated with tremendous amounts of customer and product data. Most of this information is best stored and communicated via SQL, Lightweight Directory Access Protocol (LDAP) or XML.
The key point of integration between text and these other kinds of data is a full-featured database management system. IBM and Oracle both support "WHERE CONTAINS" syntax, letting text searches and normal relational queries be joined in a single SQL statement. And since SQL systems these days can also talk XML and LDAP, those integrations are provided as well. Text-specific features are still missing from application development tools, but that's not crucial. Since relational database management systems stuff an entire document into a binary large object field, generic SQL building technology is usually all a programmer needs.
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