Oracle

Oracle has 3 types of users:System, SYS, Scott, where system and SYS differ in the ability to create databases, the SYS user logs in to create a database, and Scott is the user who learns from the novice, who can log on to the system with Scott,

CREATE TABLE Dept ( Number (2), VARCHAR2, VARCHAR2 ());CREATE TABLEEMP (empno Number(4), enameVARCHAR2(Ten), JobVARCHAR2(9), Mgr Number(4), HireDate DATE, Sal Number(7,2), Comm Number(7,2), Deptno Number(2));INSERT

Java connection to Oracle database under MyEclipseFirst step: New Java Project. Fill in the project name, other settings by default, click Done.Create a new Java class, fill in the package name and class name, tick public static void main (String []

Oracle does not have functionality such as a self-increment field, but it can be implemented through triggers (trigger) and sequences (sequence).Build a test table first:CREATE TABLE Userlogin(ID Number (6) is not NULL,Name VARCHAR2 (+) NOT NULL

1. I downloaded the Oracle_11gr2_win64. There are two packages:Note: After the decompression will be: win64_11gr2_database_2of2\database\stage\compenets\*, that is, the second under the \database\stage\components\* Copy all content to the WIN64_11GR2

When developing an ADF application, the system default primary key is unique, but the system-supplied error message is too ugly, so we can customize the error that the primary key is not unique.In addition to the primary key is unique, sometimes we

Oracle and. NET Type correspondence This is the most important thing to think about, because in most cases we use DBHelper to invoke the database because the following three places cause errors:1, the wrong SQL statement: The end of the

1. cx_oraclePython connects to the Oracle database and requires the use of the Cx_oracle package.Of the package: http://cx-Oracle.sourceforge.net/When downloading, note the version, for different versions of Oracle and platform, there are different

ORACLE DATA BLOCKThe Oracle data block is the smallest unit of the database management files.At the physical level, the Oracle data file is stored on the operating system, the smallest I/O unit is the operating system block, and the Oracle data

1. On the premise that the environment variable is well configured, strike the command #>sqlplus2. Enter username/password Login Oracle #> default we use first, user name: Scott, password: Tiger login3.A. When you log in, you can only tap Sqlplus,

Starting with the 3rd block, the block stores all of Oracle's operational records. The block structure is simple, with only the size and block body:struct BK { redo_bh blockhead; uint8_t buf[496];} REDO_BK;REDO_BKThe size is the same as the

Oracle's database operations are recorded in the redo log for undo (rollback) or redo (redo) at the time of the database exception. Redo log is also divided into online (online log) and archive (archive log) two parts.Oracle has 3 online log files

Today just met the need to do this function, conveniently search the network, several methods are listed, convenient for later reference.1 What is the merging of multi-line strings (connection strings), for example:sql> desc test;Name Type Nullable

Function:1.translateSyntax: TRANSLATE (char, from, to)Usage: Returns the string from which each character appearing in the From is replaced with the corresponding character in to.If the from is longer than the to string, then the characters that are

Original address: Https://oracle-base.com/articles/misc/efficient-function-calls-from-sqlHttp://www.oracle.com/technetwork/issue-archive/2011/11-sep/o51asktom-453438.html1. Description of the problemWe say a function is deterministic (deterministic),

First, Database modelingIi. Establishment of the tableThird, Database dictionaryIv. DML statementsV. viewsVi. IndexSeven, sequenceVIII. DDL statementsLesson 8 Overview of Data Modeling and Database Design----------------------------------------------

1. List all departments that have at least one employee.Analysis: How many employees are in each department--grouped by department numberSelect Deptno,count (*) from EMP GROUP BY DEPTNO has count (*) >= 1;2. List all employees who pay more than

Oracle authorized grant, oraclegrant GRANTPrivilege[,...]ONObject[(Column[,...])] [,...]TO {PUBLIC |Username[,...]} [With grant option]These fields are compatible with ipvs implementation, except for the following exceptions:PrivilegeSQL92 allows

View the powerful Concept from the introduction of NOTNULL integrity constraints Oracle Concept is the official book we learned on a daily basis. One reason is that there are many problems. In the final analysis, we can find some explanations and

Solution to ORA-12154: TNS: couldnotresolvetheconnectidentifierspecified when PL/SQLdeveloper connects to oracle Use the PL/SQL developer tool to connect to oracle. An error is reported during logon: ORA-12154:TNS:could not resolve the connect