Oracle

Oracle database, use the ' | | ' For string connections, let's look at the method of connecting strings in an Oracle database, and hopefully it will help you.Similar to other database systems, Oracle string connections use the "| |" string

Now it's time to delete 20 million of the data from the 50 million data table, how fast? The best way to do this is not to delete it directly:1. Use the CREATE table as2. Parallel building of primary keys and indexesThe problem came, the night

after the database was established using ORACLE10G, some data was imported into the database and an error occurred the next day when the data table was imported to the database:It's a lot of data. The reason why the data could not continue to be

Scene:oracle11gThe DB server uses sqlplus directly to connect quickly (in seconds), but with the service name, it does not respond for half a day. This issue occurs with a formal, one test.SQLPLUS:XNWZ/XNWZ soonSQLPLUS:XNWZ/XNWZ@orcl half a day, no

title: There is a teacher table T, the field is t_id,t_name; there is a student table S, the field is s_id,s_name; There is also a class table C, the field is T_id,s_id,c_name, where the value of c_name is only ' big class ' and ' Small class ',

create [or replace] PRocedure procedure name (parameter list)AsPlsql Sub-program body;After the stored procedure is finished, the stored procedure is called;There are two ways of doing this:1.exec stored procedure name ();2.pl/sqlBeginStored

Select DECODE (file_name, ' M ', Tablespace_name, Lpad ('---> ', 5) | | file_name) tablespace_name from (SELECT * FROM (Selec T tablespace_name, ' M ' file_namefrom dba_tablespaces UNION SELECT dba_tablespaces.tablespace_name,

1 Problem Solving: - -bit operating system under IIS newspaper " An attempt was made to load an improperly formatted program " ErrorReason: IIS publishes 32-bit projects under 64-bit operating system, "project-dependent DLLs cannot read, attempt to

Sql> Conn scott/scottconnected.sql> CREATE TABLE A (ID int,name varchar2 (10)); Table created. Sql> CREATE TABLE B (ID int,name varchar2 (10)); Table created. Sql> INSERT into a values (1, ' A1 '); 1 row created. Sql> INSERT into a values (2, ' A2 ')

exists and not EXISTS usage in OracleThere are two simple examples to illustrate the efficiency issues of "exists" and "in "1) SELECT * from T1 where exists (select 1 from T2 where t1.a=t2.a);When the T1 data volume is small and the T2 data is very

1, whether it is the choice of pessimistic locking strategy, or optimistic locking strategy. If an object is locked, the object will be controlled and affected by the lock. If the lock is an exclusive lock, then no other session can modify it.2, the

Database things:In the database, the so-called transaction refers to a set of logical operations units that transform the data from one state to another.To ensure consistency of data in the database, manipulation of data should be a discrete set of

Only for learning, review, in case forget, warm so know new!This is mainly about is the ALTER the use of words. first of all, I have a table that is only for learning. This table does not have a primary key constraint, a non-null constraint, or a

Oracle deadlock, oracle When two or more users wait for data to be locked, a deadlock occurs. These users are stuck in the process and cannot continue to process the business. oracle can automatically detect deadlocks and solve them, by rolling back

Merge into using usage, mergeusing Merge into [your table-name] [rename your table here] USING ([write your query here]) [rename your query-SQL and using just like a table] ON ([conditional expression here] AND [...]...) when mathed then [here you

Oracle Learning (1), oracle Learning 1. After the oracle database is installed, the system cannot log on to the database for the first time. You need to enter the sys user and change it to make it valid.2. When TNS reads the configuration, if

Sort by rownum first and then by PAGE, and sort by page by rownum Today, we suddenly thought that rownum could solve the paging problem. So we did a variety of experiments, found several articles, and finally achieved some results. The existing

Oracle Database startup and shutdown methods, oracle Database ShutdownI,OracleDatabaseSeveral startup Methods1. startup nomount is not installed and started. In this mode, you can run the following command to re-create the control file, re-build the

[04] index and SQL statement Optimization1. Index concept The index of a database is similar to a book directory. The index points to the location where the query content is located (such as the page number in the book), reducing the number of disk

Mybatis dynamic SQL, mybatissql Glossary OGNL expression OGNL, called Object-Graph Navigation Language, is a powerful expression Language used to obtain and set attributes of Java objects, it aims to provide a higher abstraction level to navigate