Oracle

I. Introduction of the Platform environmentSystem: Win7 64-bitDevelopment tools: vs +oracle 11Project: ASP. NET Web ApplicationDeployment: IIS Local Application Mode　　Ii. Description of the problemThrow exception when opening database connection

One, sub-proceduressubroutines are named PL/SQL blocks that are stored in the database and can be wie to specify parameters that can be called from any database client and application. Subroutines include stored procedures and functions.Sub-programs

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)

method One: by To_number function exception to judgeCREATE OR REPLACE FUNCTION is_number (Str_ VARCHAR2) RETURN VARCHAR2IsNUM_ number;BEGINNum_: = To_number (STR_);RETURN ' Y ';EXCEPTIONWhen OTHERS ThenRETURN ' N ';END Is_number;/Sql> Select

Oracle Learning website http://www.oracle-base.com to get a sense of the article, thatOracleThe basic skills are very solid. (English)http://asktom.oracle.com/pls/apex/f?p=100:1:0 ; mainly experts to answer questions of the site, biased to improve

simple use of syntax:Mysql:ALTER TABLE = MyISAM; ALTER TABLE ADD fulltext (abstract); SELECT * from Dataset_ods WHERE MATCH (abstract) against ('XX');Oracle:CREATE INDEXFulltextindex_dataset_ods onDataset_ods (ABSTRACT) Indextype isCtxsys. CONTEXT;

The following SQL execution time is decremented by ordinal.1, dynamic SQL, no bound variables, each execution of a hard parse operation, occupy a large pool space, if the pool space is insufficient, the other SQL statements will cause the resolution

When you import/create an Oracle database table, sometimes we examine the discovery, import/create table, and the table space created is not the default table space we want. At this point we need to modify the user's default tablespace and then

The provides a function for generating a UUID in Oracle SQL sys_guid: http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/ functions187.htm#i79194 Http://en.wikipedia.org/wiki/Universally_unique_identifier sql> Select Sys_ GUID ()

Create and manage tables 1 (learning notes), create and manage learning notes Common Data Types Syntax for creating a table: Create table username. TABLE Name (field Name field type [DEFAULT value] field Name field type [DEFAULT value]

Function (learning notes), function learning notes Function (storage function)It is also a convenient storage structure. User-defined functions can be directly called by SQL statements or PL/SQL. The biggest difference between a function and a

Common oracle functions-decode The Decode function is very useful in actual development and has powerful functions. Combined with other functions, it can simplify a lot of work; DECODE (field, condition 1, result value 1, condition 2, result value 2

Dynamic SQL (learning notes) and dynamic SQL learning notes Dynamic SQL Execute immediate dynamic SQL string [BUCK COLLECT] INTO custom variable, | record type USING [IN | OUT | in out] bound parameters] [RETURNING | RETURN] [bulk collect] INTO

What are the usage and differences between Decode and nvl functions in Oracle?Decode Decode (condition, value 1, translation value 1, value 2, translation value 2 ,..., default Value... else if... else has the same meaningNVL Format:NVL (string1,

Multi-Table query (learning notes), (learning notes) Syntax: SELECT [DISTINCT] * | column name [AS] alias ,........ FROM table name 1 [alias 1], table name 2 [alias 2],... [WHERE condition (s)] [order by sorting Field 1, ASC | DESC, sorting Field 2

Join Operation (learning notes) and Join Operation learning notes There are two connection operations for data tables in the database: Internal Connection:It is also said that the condition for equi join to eliminate Cartesian Product in where is

Set Operations of data (learning notes) and computing learning notes A set operation is a binary operator. A total of four operators, and, difference, intersection, Cartesian Product Set operation Syntax:   Query statement [UNION | union all |

General functions (learning notes), general function learning notes -- **************** Common functions-- NVL processing NULL-- NVL (number | column, default value). If the displayed number is NULL, the default value is used.-- NVL2 (number |

Lock (learning notes), learning notes Row-level locking and table-level locking: Row-Level Lock: When you execute, INSERT, UPDATE, DELETE, and select for update statements, ORACLE will implicitly implement the locking of records. If the transaction

Oracle Performance Optimization Operation 14: using function-based indexes As mentioned above, any operations on columns may cause full table scanning. For example: select * from emp where substr (ename, 1, 2) = 'sm '; However, this type of