oracle sql variable in query

*sql optimization based on ORACLE11GR2 reading notes * Third, cursor in OracleThe cursor in Oracle is a vector of SQL parsing and execution in an Oracle database and is a data structure for C (Oracle is written in C).There are two types of cursor in

Oracle-based SQL Optimization MethodologyThe ultimate goal of SQL Optimization in Oracle databases is to shorten the execution time of target SQL statements. To achieve the above purpose, we usually have the following three methods to choose from:1.

With the specific input values, the selectable rate (selectivity) of the Where condition of SQL and the number of rows (cardinality) of the result set may vary, The value of selectivity and cardinality directly affects the CBO's estimate of the cost

In Oracle, for a committed SQL statement, there are two alternative parsing processes, one called hard parsing and one called soft parsing. A hard parsing requires many steps, such as parsing, making the execution path, optimizing the access plan,

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

Oracle SQL * plus is a client tool that interacts with oracle. In SQL * plus, you can run the SQL * plus command and the SQL * plus statement. The DML, DDL, and DCL statements we usually call are SQL * plus statements. After they are executed, they

[ 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

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

When importing data from IMP in Oracle, hybriddb for MySQL prompts that the character set is inconsistent. The imp import and exp export functions of Oracle are often used in the production environment for data migration. The character set is

Original address: http://www.cnblogs.com/lyhabc/p/3367274.htmlBefore reading this article, you can read the following article firstSQL Server's unique task scheduling algorithm "Sqlos"Task Scheduler for SQL Server Sqlos [go]Translated