Oracle

First, some conceptsDefined:Primary Key-uniquely identifies a record, cannot be duplicated, is not allowed to be emptyForeign key--the foreign key of the table is the primary key of another table, the foreign key can have duplicate, can be a null

Triggers are stored as separate objects in the database, and unlike stored procedures, stored procedures start running through other programs, and triggers are started by an event. 1. Trigger characteristics 1> triggers are automatically run when an

In is used in Oracle string, but no data is found1 string " SELECT * from TB_YBSH where ID in:ids " ; 2 New OracleParameter ("ids", IDS); 3 DataTable dt = dbhelperora.executetable (getmodel,p);Direct stitching is availablestring " SELECT * from

In 12C, when a column is defined as "invisible," the SQL statement without direct access to the column is unable to see the "invisible column", and the statement that explicitly references the "invisible column" can access and manipulate the

In previous versions, the parent table could not be truncate directly when there was a foreign key constraint. In 12C, a cascade operation attribute was added to the truncate operation.If you create a FOREIGN key constraint, use "on Delete

Oracle provides the ability to store PL/SQL blocks in a database and to run it anywhere, a PL/SQL program block called a stored procedure or function.The difference between stored procedures and functions: the function needs to return data to the

To view the Oracle database character set:Sql> Select Userenv (' language ') from dual;USERENV (' LANGUAGE ')--------------------------------------------------------------------------------American_america. we8mswin1252sql> shutdown immediate;sql>

This problem encountered many times, every time the system was met once, but always take half a day to fix.Today it takes a couple of hours to settle, and finally a clear understanding must be recorded.One, download decompression, do not build any

Create a temporary table spaceCREATE Temporary tablespace test_tempTempfile ' C:\oracle\product\10.1.0\oradata\orcl\test_temp01.dbf 'SIZE 32MAutoextend onNEXT 32M MAXSIZE 2048MEXTENT MANAGEMENT LOCAL;Create a user table spaceCREATE tablespace

rownum and rowID are pseudo-columns, but the root of the two is different, rownum is to assign a logical number to each row based on the results of the SQL query, so your SQL will result in a different final rownum, but rowID is physically

Use OracleDataAccess.dll to access the Oracle database, encountered in Chinese garbled situation.The solution is as follows:1 Viewing character set encoding, starting sqlplus on the database server sideSql->select userenv (' language ') from

The Oracle statements are as follows:How to use: Start With.....connect by Prior. Where start with the following condition 1 is the parent node's query criteria, connect by prior followed by the condition 2 is the same as the record's parent node in

Oracle Learning Note onepermissions are divided into sysdba,nomal, the system comes with two users , the starting password is empty . the user is: System,sys. Login SYSTEM should use sysdba permissions to log in, if you forget the password, open the

I. VARCHAR2 (10) and number should be converted why type?When Oracle turns into MySQL:VARCHAR2 (10) can be turned into varchar (10)Number depends on what type of data is stored in Oracle:1, if the integer type, then MySQL, with an int can be;2, if

Three types of collection operations are available in Oracle: and (UNION), intersection (INTERSECT), poor (minus) UNION: Combine the results of multiple queries into one query result and remove duplicate values UNION All:

Oracle Database batch processing files and oracle Database Batch Processing Directory structure Initialization Script |----orcl_sql|----init_user.sql|----tab_home.sql |----TAB_USER.sql |----init.bat Init. bat @ Echo off @ echo success @

Ora-01034, ora-27101 troubleshooting Error cause: Solution: ora-27101 There may be 2 scenarios, which may lead you to encounter ORA-271011) Invalid ORACLE_HOME and ORACLE_SID (configured in environment variables)2) Database is down (check

The best way to record errors in oracle stored procedures When your application calls a stored procedure and dozens or hundreds of nodes, it is difficult to find an error. At this time, I suggest writing it to the database, below is a demo I made. 1.

Vertical table and horizontal table, vertical table horizontal table Vertical vs horizontal The following example shows the traditional horizontal table structure: 　　Table HR 　 　　ID 　　Surname 　　Name 　　Department 　　Gender

Mysql, SQL server, oracle Database paging query and Analysis (Operation Manual), mysqloracle 1. mysql paging Query Method 1: select * from table order by id limit m, n;   This statement means to query m + n records, remove the first m records, and