Oracle

In addition to the recommended use of the PL/SQL Developer tool for Export Import (http://www.cnblogs.com/whylaughing/p/5983490.html) of Oracle, there are more commonly used cmd command line modes: 1, Data export:1 full export of database test, user

In general, the database language can be divided into the following 5 categories:1, Data Definition Language DDL (Language), used to change the database structure, including creating, modifying and deleting database objects. Includes Create, alter

1: Increase operation Public intaddtest (Testvo TV) {byteBz[] =tv.getbz (). GetBytes (); Lobhandler Lobhandler=NewDefaultlobhandler (); String SQL= "INSERT into Test (NAME,AGE,BZ) VALUES (?,?,?)"; returnJdbctpl.execute

There 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 large, the query efficiency of T12)

Early this morning because to do some operations in the database, is about the two tables associated with the update, but the statement how to write is not correct, always error, so scared (afraid not to complete the operation in time) to check, NND,

Redo redo logs are the basis of Oracle Database Recovery (recovery), but in many cases it is possible to speed up the completion of SQL statements by disabling the generation of redo logs, which is what we call nologging operations, which are mostly

--Calculate Plsql processing time difference--QzqDeclaretime1timestamp;--Start TimeTime2timestamp;--End TimeSum1 Number(9);--Time difference (s)begintime1:=To_timestamp (To_char (Sysdate,'YYYY-MM-DD Hh24-mi-ss'),'YYYY-MM-DD hh24:mi:ss.ff9');

--Query ColumnsSelectT.sname,t.ssex,t.class fromStudent T--T alias;Select * fromStudent T;--* represents all data in the query tableSelect * fromStudent TwhereT.sclass='95031';--t.sclass= ' 95031 ' for the condition of judgment, with where

--built-in functions--aggregate function returns a single valueSelect Count(*) fromStudentwhereSclass='95031';--count () record number of barsSelect sum(degree) fromScore T;--Sum (degree) to find the sum of resultsSelect avg(degree) fromScore

--DeleteDrop TableDianfei;--Create a tableCreate TableDianfei (UoNvarchar2(Ten) not NULL, Mmonthvarchar2(6) not NULL, DDF Number(6,2) not NULL, Djftime date not NULL, Djfztvarchar2(3) not NULL, DSYJF date not NULL);--NotesComment on TableDianfei is '

1.sql Execution Process1> parsing (determining whether an object exists, whether there are permission queries, semantic parsing, checking the cache for the same SQL, and so on)2> optimization (CBO determines the optimization mode, determines the

1.sql Execution Process1> parsing (determining whether an object exists, whether there are permission queries, semantic parsing, checking the cache for the same SQL, and so on)2> optimization (CBO determines the optimization mode, determines the

Recursively querying all tree structures:SELECT * FROM tableConnect by Prior id= parent_idStart with id= head office IDThe above SQL statement query out of the tree structure has three branches!Recursive query out of the tree structure, with

The parameter passed in as long as the parameter of the list type is OK ... 1, BULK Insert insert into T_city_index ( I D,city_code ) Select Seq_city_index. nextval,cd.* from ( Select #{item.citycode,jdbctype=varchar},

--Create a temporary tablespace (not required)Create temporary tablespace zwtestTempfile ' D:\Java\oracle\oradata\zwtest.dbf 'Size 50mAutoextend onNext 50m maxsize 20480mExtent management Local;--Create TABLE spaceCreate Tablespace

With ASThe with as phrase, also called the subquery section (subquery factoring), allows you to do many things, defining a SQL fragment that will be used by the entire SQL statement. Sometimes it is to make the SQL statement more readable, or it may

I. Database language classificationTwo. DML Data insertionQuery the data in one table and insert it into another table.CREATE TABLE student (ID number,name varchar2 (),age number);INSERT into student select Id,name,age from Student1;INSERT INTO

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Overview　Oracle installation on Linux and Windows is not the same, the company is Oracle on the Linux system, there is no way to study the use of Oracle under Linux, Oracle default does not support the installation of CentOS system, so when

1. View database Character Set informationSql> select * from Nls_database_parameters;Where Nls_characterset is the character set of the current database.2. Client Character SetThe parameters for the client character set are Nls_lang.In Windows,