if condition in sql oracle

*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

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 Language Oracle Pl/sql Language Foundation 2002-8-23 Oracle Pl/sql Language Basics Pl/sql is Oracle's extension of the standard database language, Oracle has integrated PL/SQL into Oracle servers and other tools, and more developers and

1. A question describes how an SQL statement is executed in a database? I believe many people will be interested in this issue. Of course, it is a huge problem to fully describe the lifecycle of an SQL statement in the database, it covers a series

Source: Drill down into the MySQL kernel1 Problem DescriptionHow does a SQL work in a database? I believe a lot of people will be interested in this problem. Of course, to fully describe a SQL in the database life cycle, this is a very big problem,

The Oracle tutorial you are looking at is the introductory Foundation for Oracle Pl/sql languages. Pl/sql is Oracle's extension of the standard database language, Oracle has integrated PL/SQL into Oracle servers and other tools, and more developers

1. Description of the problemHow does a SQL work in a database? I believe a lot of people will be interested in this problem. Of course, to fully describe a SQL in the database life cycle, this is a very big problem, covering the SQL lexical parsing,

The ORACLE tutorial is the basics of Oracle PL/SQL language. PL/SQL is an extension of ORACLE's standard database language. ORACLE has integrated PL/SQL into ORACLE servers and other tools, in recent years, more developers and DBAs have started 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,

Methods of accessing dataThere are two types of data in the Access table: 1, direct access to table 2, first access to the index, and then back to the table1, direct access to the table of two ways:①, full table scanFull-table scanning refers to