Oracle

Advanced subquery subquery (subquery)Knowledge Point one: the relationship between multi-table joinsFor example, want to know which kind of books have been lent out.Select DISTINCT C.parent_catagory, c.sub_categoryFrom category C, Bookshelf b,

To implement string segmentation, the algorithm is as follows:Algorithm 1:DECLARERemove_column myvarray_list; Xvarchar( +); Subvarchar( +); I Number; J Number; C Number; Rcount Number;BEGINRemove_column:=Myvarray_list ();--init array.Sub:='ORA-26786:

Oracle in Extents Characteristics:1: A extent consists of multiple blocks that are connected, and multiple extents form a segment,2:oracle When allocating space for segment, extent is the unitSo extents brings benefits:1: Space

1. Check if the database is turned on for flashback (view two nodes Rac1 and RAC2 Open Archive log)Sql> archiveloglistSp2-0734:unknown command Beginning "Archivelog ..."-rest of line ignored.Sql> Archive Log ListDatabase log mode No Archive

1. Rename the table space:alter tablespace original tablespace name rename to new table space namePS:(1) system and Sysaux table spaces cannot be duplicate names(2) If any of the data in the table space is offline or the table space is offline, you

Partition Table PurposePartition table by the judge of the partition column, the partition column of different records, put into different partitions. Partitions are completely transparent to the application. Oracle's partitioned tables can include

Use of the Oracle trunc () function1.TRUNC (for dates)The date value that the Trunc function truncates for the specified element.Its specific syntax format is as follows:TRUNC (Date[,fmt])whichDate a datetime valueFMT date format, which is truncated

When a database user inserts, updates, deletes data from a table in a database, or increments a table's primary key or the table's index,There are often errors such as Ora-00054:resource busy and acquire with nowait specified.The main reason is that

This article is a record of an Oracle database Undo table Space Full analysis process, the main collation, carding the colleagues analysis of the idea. The process is as follows:In the morning, I received an alarm message from the database server's

The situation I encountered:When querying a table with a SELECT statement, followed by for update,Select from Table for updateWhen you modify the data in the table, but do not have a commit to turn off PL/SQL, the next time to open the execution

There are two methods: SCN and time stamp two methods of recovery.I. Recovering deleted and committed data through the SCN1. Obtain the SCN number of the current databaseSelect Current_scn from V$database; (Switch to SYS user or System user

C:\users\administrator>echo%oracle_sid%%oracle_sid%C:\Users\Administrator>SetOracle_sid=Orclc:\users\administrator>sqlplus/ asSysdbasql*plus:release11.2.0.1.0Production on Sunday September - the:Geneva: - .Copyright (c)1982, ., Oracle. All rights

Bind variable (bind variable) We often use it in writing plsql, so let's take a look at the difference between static SQL in Plsql and dynamic SQL in bound variablesDECLARE v_value_a varchar2 (100);    V_value_b varchar2 (100);    V_name VARCHAR2 (a)

User management:1. Create a user (to log on with DBA authority to create a Sys/system login)Create user username identified by password (password starts with a letter);2. Change the password to the user1>alter user username identified by new

None of the previous versions of Oracle 12c are self-contained, and if you need to use a self-add column, you need to sequence. DROP TABLE CustomerOrder PURGE;CREATE TABLE CustomerOrder(ORDERID number is not NULL,PRODUCTID

SELECT * FROM teacher--female teacher number, nameSelect Tno,tname,gendar from teacher where gendar= ' woman '--Han's female teacher number, name, ID numberSelect Tno,tname,tid from teacher where gendar= ' women ' and tname like ' Korean '--Salary

SELECT * FROM teacher where tno>1090--Recall the MySQL page beforeSELECT * FROM teacher limit (pageIndex-1) *pagesize,pagesize--oracle need pseudo-columns for paging? What is a pseudo column!--pseudo-column can be queried from the table to! Each

Oracle user-to-table space relationshipsuser = MerchantTable = CommodityTable Space = Warehouse1.1 businesses can have a lot of goods, 1 products can only belong to one business2.1 items can be placed in warehouse A, can also be placed in warehouse

Never give up, everything is possible!!!Only to find a way to succeed, not to find excuses for failure!Oracle database Backup 1. File ViewThe data files, control files, and log files are viewed as follows:From V$datafile; -- View data file from

Oracle 12c far sync active replicuard architecture uses DGMGRL for configuration managementI have been learning Oracle 12C database recently, so I have reviewed some documents. Here I will mainly introduce how to configure the DG Broker on the