oracle sql count if

SQL turning is a tool in the Quest Central software produced by Quest Corporation. Quest is an integrated, graphical, Cross-platform database management solution that can manage Oracle, DB2, and SQL Server databases simultaneously. Introduction to

Oracle SQL Performance 1. ORACLE optimizer:. RULE (based on Rules) B. COST (COST-based) c. CHOOSE (optional) sets the default optimizer. various declarations of the OPTIMIZER_MODE parameter in the ora file, such as RULE, COST, CHOOSE, ALL_ROWS,

Count1) with Count (*) Comparison: If your data table does not have a primary key, COUNT (1) than COUNT (*Fast If there is a primary key, then the primary key (the Federated primary key) as the count condition is also more than count (*) to be quick

1) count (1) compared to COUNT (*):1. If your data table does not have a primary key, then count (1) is faster than COUNT (*)2, if there is a primary key, then the primary key (Union primary key) as the count of the condition is also faster than

Oracle basic concepts and comparison with informix I. ConceptsUser: informix directly uses the user management system of the operating system. Generally, root and informix are used as super operators to manage other users. Oracle has its own user

1. The difference between count (1), COUNT (*), and count (column name)Believe that you are always at work, or in the study of Count () in the end how to use faster. There has been a lot of doubt, some people say that count (*) faster, some people

[ Oracle-based SQL Optimization ]Oracle-based SQL optimization"Bo Master" Gao Ruilin"Blog Address" http://www.cnblogs.com/grl214 A Written Intent description In the early stage of the system development, due to less

NonsenseIt's been about N years since the last time I contacted Oracle database, and the way Oracle works and some of the dots is special, it feels like a wonderful thing! Recently regained memory, has been tossing Oracle, because Oracle is

The racle database system is a complex software system. Without understanding its internal structure principles and relationships, it is impossible to design and Compile High-Quality application software systems or manage a complex application

1. Oracle startup and Shutdown 1. In a single-host environment To start or shut down the Oracle system, you must first switch to the Oracle user, as shown below: Su-Oracle A. Start the Oracle SystemOracle> svrmgrlSvrmgr> connect internalSvrmgr>