Oracle

1. Select the appropriate Oracle OptimizerThere are 3 types of Oracle Optimizer:A. Rule (rule-based) B. Cost (based on costs) c. CHOOSE (selectivity)The default optimizer can be set by various declarations of the Optimizer_mode parameter in the Init.

I. Maintaining the integrity of the dataData integrity is used to ensure that database data complies with certain commercial and logical rules, and in Oracle, data integrity can be implemented using three methods of constraints, triggers,

One, character functionsThe character function is the most commonly used function in Oracle, so let's see what the character functions are:Lower (char): Converts a string to a lowercase format.Upper (char): Converts a string to an uppercase

The Dbms_output package is primarily used to debug PL/SQL programs, or to display information (displaying message) and reports in the Sql*plus command, such as we can write a simple anonymous PL/SQL program block that is used for some purpose dbms_

Oracle Learning--buffer Cache in-depth analysis650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M02/40/BE/wKioL1PPVxOwPpjTAAL_LJN_ltc591.jpg "title=" 1.png " alt= "Wkiol1ppvxowppjtaal_ljn_ltc591.jpg"/>Server process and database buffer

function is used to return specific data, and when a function is established, the function header must contain a return clause. The body of the function must contain the data returned by the return statement. We can use CREATE function to create

Tag:os    Data    io   for   cti   re     --Query the data generated by the day in a table-the CDate field in the original table Mobilefrends has an index on it: CREATE INDEX mobilefrends_cdate_idx on mobilefrends (CDate); --------------------------

Example 1: Creating a sequence:CREATESEQUENCE ABC INCREMENT by 1START with 1MAXVALUE9999999999nocycle NOCACHE; a grammatical explanationCREATESEQUENCE sequence Name[INCREMENT by N] --1.[START with N] --2.[{Maxvalue/minvalue n| Nomaxvalue}]

First, IntroductionThis section focuses on how to manage permissions and roles in Oracle, and what the difference between permissions and roles is.When a user is just established, the user does not have any permissions and cannot perform any action.

Demand:Match the phone number, the first bit can be +, can not +, the back of all if the number, such as:+86135941566586136595585551356856455are legal.+aa156945555aa1359556666Aaddssdfdfsdare not legal.Regular:[SQL]View Plaincopyprint? Sql>

The content mainly includes:(1) Three kinds of cycles and their simplification(2) Use of cursors(3) Exception handling(4) Stored procedures(5) Storage function(6) Trigger(7) Other PL/SQL operationsDefine variables---------------Loop loop-------------

I am in the process of learning Oracle's own sentiment and the online other great God's experience, there is nothing wrong place hope everyone correct!Principle One: Note the connection order in the WHERE clause:Oracle uses a bottom-up sequential

rollback Segment Overview The rollback segment is used to hold the value before the data modification, including the position and value before the data is modified. The head of the rollback segment contains information about the rollback

What is TNS?TNS is part of Oracle NET, a tool dedicated to managing and configuring Oracle Database and client connections, and in most cases the client and database must be configured for TNS, but in rare cases, you can connect to an Oracle

The following is an example of importing and exporting, and seeing an instance of import and export is basically done, because importing and exporting is simple.Data export: 1 The database test is fully exported, user Name System Password Manager

I. What is Oracle archive modeThe Oracle database has an online redo log, which records changes made to the database, such as inserting, deleting, updating data, etc., which are recorded in the online redo log. A generic database must have at least 2

In the development of the report, it is unavoidable to encounter the problem of row to column.For example, in the case of Scott's EMP in Oracle, you can use "Row to column" to count the number of people in each position in each department:The

Understanding of Oracle outer connections (left/right/full) and inner using experimental methods)Oracle's left join, right join, and (+) Outer Join types are always confused. The experiment is used to deepen the understanding of the connection type

Notes for writing high-performance SQL statements, high-performance SQL statements 1. is null and IS NOT NULLNull cannot be used as an index. Any column containing null values will not be included in the index. Even ifIf there are multiple columns

Oracle obtains detailed information such as the current user table and field. Make a note for your reference only SELECT d. TABLE_NAME tbName, // table name COALESCE (t. COMMENTS, '') tbDesc, // table comment. COLUMN_NAME columnName, // field name.