Oracle

1. Intersect operationsReturns the same part of the query result, indicating the intersection of them. SQL> select * from ABC2 intersect3 select * From abc2; 2. Minus operationsReturns the row records that are different from the results of the

1. log on to Oracle AS A DBA A: Start Oracle services. B: Run cmd to open the command window. C: Enter "sqlplus sys/root as sysdba" in the command line. The root is the logon password. In this way, you can successfully log on to Oracle.

Cartesian sets are generated under the following conditions: • omitted join conditions • invalid join conditions • all rows in all tables are connected to each other. To avoid Cartesian sets, a valid join condition can be added to the WHERE clause.

Subquery Syntax: subquery (internal query) is executed once before the primary query. The subquery results are used by the primary query (external query ). Note: subqueries must be included in brackets. Place the subquery on the right of the

There may be two reasons. Many of the reasons found on the Internet are the second reason, which is also common: 1. Oracle's Integrated Oracle Servlet Engine occupies port 8080, and Tomcat's default port is also 8080, Tomcat port can be easily

Oracle indexes mainly include btree and bitmap indexes. By default, most btree indexes are used.Unique index, clustering index, and so on. btree is used in OLTP to speed up query. The bitmap index is an interesting place in Oracle. It is mainly used

Two minor issues in dbms_output of Oracle     1. If the content of dbms_output.put_line cannot be displayed, You need to first input set serveroutput on in the command line. Just repeat it and then the content of dbms_output.put_line will be

I couldn't connect to the database at one time. I checked many materials and finally found the answer. First, ensure that the database service starts.In the database view of myeclipse, right-click-> New to bring up the database driver window,Select

1. b-trees, short for balanced trees, are the most common type of database index. as the name suggests, B-tree is a structure of the Balance Tree. [Note that B indicates the balanced balance, rather than the binary.] B-tree indexes are also the most

There are several common methods: 1. Use the PL/SQL Dev Tool 1. directly file-> New-> explain Plan window. Execute SQL statements in the window to view the plan results. Among them, cost indicates the CPU consumption, unit is n %, cardinality

Http://advance0683.iteye.com/blog/1055226 % Rowtype: indicates that this type is the row data type. It is stored as a row of data. A row has many columns, which is equivalent to a row of data in the table or a row of data in the cursor.   % Rowtype

Http://wanwentao.blog.51cto.com/2406488/516358 Delete from table name where condition; Note: deleting a record does not release the occupied data block tablespace in Oracle. It only marks the deleted data blocks as unused. To delete all records in

-- Analyze. sqlset serveroutput on size 100000 Declare V_per number (3 ); V_start number: = dbms_utility.get_time; V_end number; Beginfor REC in (select segment_name, segment_type, Ceil (sum (bytes)/1024/1024) segment_size From user_segments group

1. stop all Oracle Services 2. use Oracle universal installer to uninstall oracle3. delete all the primary key Oracle databases under hkey_loacal_machine/software from Oracle with a key value (start à run à Regedit) on the registry. 4. Go to the

Database startup and Shutdown On Windows, the database can be opened by starting related services. Use the service options of the control panel or the command line mode, such:Net start oracleserviceateiYou can open related services. This depends on

1. tkprof is an executable tool for analyzing Oracle tracking files and generating more user-friendly and clear output results. C:/Oracle/ora92/bin/tkprof.exe 2. Full name of tkprof References Http://www.itpub.net/showthread.php? S =

In many cases, the local test environment cannot simulate all the performance problems of the customer's production system. It may take only a few minutes to quickly run in the local environment, but it usually takes several hours for the customer

1. Perform a statspack when the system works well! Save the result file as the criterion for future judgment. 2. create a table script for storing execution plans in Oracle as follows: -- create a table named plan_hashes (SQL _text varchar2 (1000),

First go to the official website to download the appropriate version, I am win7 64-bit system, so download the latest instantclient-basic-windows.x64-11.2.0.2.0 and instantclient-sqlplus-windows.x64-11.2.0.2.0, decompress to the same file, such as

Oracle integer functions include the following:1. Round (large) Select Ceil (-1.001) value from dual to large carryCeil (-1, 0.12)-----------02. Round (small) Select floor (-1.001) value from dual to small carryFloor (-1, 0.12)-------------1 3.