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Database-Tutorials Database Oracle Primary Keys and Unique Columns in Oracle and SQL-Server Tutorial The SQL-92 standard requires that all values in a primary key be unique and that the column not allow null values. Both Oracle and Microsoft SQL Server enforce uniqueness by automatically creating unique indexes whenever a PRIMARY KEY or UNIQUE constraint View Rating

Database-Tutorials Database Oracle How to measure Index Selectivity Tutorial B*TREE Indexes improve the performance of queries that select a small percentage of rows from a table. As a general guideline, we should create indexes on tables that are often queried for less than 15% of the table's rows. This value may be higher in sit View Rating

Database-Tutorials Database Oracle How to specify the WHERE clause for UPDATE / DELETE Tutorial Sometimes multiple users are accessing the same tables at the same time. In these situations, you need to decide when to allow your application to update the database. If you allow your application to always update the database it could overwrite changes View Rating

Database-Tutorials Database Oracle Parallel Clause and Small Tables Tutorial If you have multiple CPUs available you may come up with the idea to set parallel execution on every table. The Oracle Optimizer should decide about the degree of parallelism or even if is necessary to use parallel execution at all. What's a great thing o View Rating

Database-Tutorials Database Oracle Analytic Functions in Oracle 8i and 9i Tutorial Analytic Functions, which have been available since Oracle 8.1.6, are designed to address such problems as 'Calculate a running total', 'Find percentages within a group', 'Top-N queries', 'Compute a moving average' and many more. Most of these problems ca View Rating

Database-Tutorials Database Oracle The Secrets of Materialized Views Tutorial In this article you'll find out what materialized views are, what they can do and, most importantly, how they work - a lot of the ' magic ' goes on behind the scenes. Having gone to the trouble of creating it, you'll find out how to make sure that your ma View Rating

Database-Tutorials Database Oracle Global Statistics vs. Histograms with DBMS_STATS Package Tutorial Optimisation is the process of choosing the most efficient way to execute a SQL statement. The cost-based optimiser uses statistics to calculate the selectivity of predicates and to estimate the cost of each execution plan. View Rating

Database-Tutorials Database Oracle Introduction and Examples to Oracle Advanced Queueing Tutorial Oracle introduced powerful queuing mechanisms where messages can be exchanged between different programs. They called it Advanced Queuing AQ. Exchanging messages and communicating between different application modules is a key functionally becoming import View Rating

Database-Tutorials Database Oracle Connecting to Oracle 9 using the Microsoft .NET Framework Tutorial In this Tip we show how to connect to an Oracle 9.2.0 database from the .NET Framework using C#, MDAC and ODBC View Rating

Database-Tutorials Database Oracle Rebuilding Oracle8 Object Types Tutorial How can I rebuild an Oracle8 object type if it has table dependencies? Hey, that's a great question. Unfortunately, I haven't found a great answer. The basic problem is that Oracle offers two schema modification tools for object types, neither of which go View Rating

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