Oracle

The usual time format masks are as follows:Mask element meaningYYYY four-digit years (e.g. 2005) yearYY Two-digit year (e.g. 05)Q Quarter (1-4)MM month (01-12) monthNumber of weeks of WW years (1-53), of which the first week is the first day of the

In most cases, the data can be backed up and restored with Oracle data import and export (no loss of data).Oracle has a benefit, although your computer is not a server, but you installed the Oracle client and established a connection(with the net

Here's a look at the monitoring configuration in the Oracle network:650) this.width=650; "src=" Http://s2.51cto.com/wyfs02/M01/86/57/wKioL1e8W1XhBxylAABNjdsDQZs648.png "title=" Qq20160823221132.png "alt=" Wkiol1e8w1xhbxylaabnjdsdqzs648.png "/>How

VARCHAR2 (6) Zhang San--two bytes in JBK, three bytes in UTMCHAR (6) Zhang San--can be used to determine the length of the CharCLOB--large storage, nothing less, when the extra 4000 bytes, will be used to store lob, efficiency is lowerNumber 100.123-

Batch file (. bat) @echo off Echo ================================================ Automated backup scripts for Oracle databases in the Echo Windows environment Echo 1. Use the current date to name the backup file. Echo 2. Automatically

There are two main analytic functions used in the work, one is sum () over (partition by ... order by ...) The other one is lead (lag) over (|partition By|order by)Sum does not need to say much, mainly by the partition by the field, the total, the

　　1, the database instance: After the database is created there will be a series of memory space for the database service and the acquired process, known as an instance of the database. Each database will have at least one instance for its service.

type char (length) varchar2 (length) number (p,s) date timestamp clob blob

Oracle Database transactions1. What is a transactionIn a database, a transaction is a logical unit of work, a transaction consists of one or more SQL statements that complete a set of related behaviors, ensuring that the operations of this set of

Cascade Delete, such as when you delete a table and then add the keyword, will delete the table and delete the relationship between the tableotherObject1. Cascade delete the information in table A, when the field in table A refers to the field in

These four functions are a bit like the functions in Java, first of allTrunc (Number,[decimals]) This function is similar to the Intercept functionNumber: Indicates that you want to enterDecimals (decimal): Indicates the number of digits you want to

SQL (strutured query Language): Structured Query LanguageSQL can be divided into:　　 Data Definition language (DDL):D ATA definition LanguageUsed to create, modify, and delete data Objects ( databases, tables, and so on):(1) Create: Construct the

1. Simple example of stored procedureCREATE OR REPLACE PROCEDUREstored procedure name (parameter in, parameter out) as--variable declarations, with each declaration ending with a semicolon. Can be initialized at the same time as the

Oracle Basic data types:Oracle's basic data types are categorized by type: String type, data type, date type, LOB type, and so on.1. String Type:①char: fixed-length string that stores up to 2k bytes, and defaults to a length of 1 bytes without

One, character functions 1. Casing control function --lower: Make the letter lowercase----upper: Make the letter uppercase----INITCAP: Make the first letter of the character uppercase--select lower (' ABC '), Upper (' sql '), Initcap (' HeLlo

Oracle System account password expiration resolution.The password for the system account is valid for 180 days, and when the password hint has expired,This can be resolved in the following ways:1> input sqlplus in DOS window, prompt to enter account

Native environment: 64-bit Win7, 64-bit Oracle Desktop class installedServer environment: 64-bit Windows Server 2008, 64-bit Oracle server-sideProblem: The native SQL Developer database is not a problem, the WinForm program connection is not a

Turn.The Oracle Supplemental logging feature can be divided into the following types of functions: Minimum (Minimal), support for all fields (all), primary key (primary key), unique key support (unique), support for foreign keys ( Foreign key).

1. Concept A cursor is a handle or pointer to the memory area that SQL handles. An implicit cursor is automatically created when a PL/SQL block is used to execute a DML statement or a SELECT statement that returns only a single row of results. If

Oracle under Linux is in a running state after installation is complete. After restarting the machine, Oracle does not add Oracle to the Windows service as it did under Windows, and the Orcle service needs to be started manually under Linux