Oracle

Oracle9i introduces a new SQL statement, which can be used to connect two tables in one statement.Before using update to update records in both tables, or using insert to add records that do not exist in the two merged tables, you must write two SQL

the clustered index determines the physical sequence of data in the table. The clustered index is similar to the phone book, which sorts data by last name. Because clustered index specifies the physical storage sequence of data in the table , a

1.Database index You can apply the index concept to a database table. When a table contains a large number of records, it takes a long time for Oracle to look up the close-up records in the table-just as it takes a long time to look up the book

Recently, I attended the OCP training. The lecturer said it was too fast. I have been using sqlserver for a long time, and many things have to be done. Upsert function: Merge into Using On ()When matched then When not matched then ;

Oracle's online redefinition Table Function In a high-availability system, changing the definition of a table is a tough issue, especially for a 7 × 24 system. The basic syntax provided by Oracle can basically meet general modification

During data export today, because the user name and password use special characters, an error occurs. Code: "EXP-00056: encounter OracleError 12154 ", the reason for searching online, which needs to be expanded with quotation marks, but the OS is

Recently, I have done some database conversion work, mainly from SQL Server to Oracle. I encountered many problems during the process. Now I will make a small summary to help my friends who have the same requirements. Database elements, such as

To avoid SQL-injection, all the update, insert, delete, and select statements are written in the form of parameters. Update tablename set filedname =: fd1 where id =: ID ID: The Oracle type is dbtype corresponding to varchar2.String The

ArticleDirectory Comparative analysis: Practical Application Due to the influence of web page rendering speedProgramThe data in a grid containing thousands or tens of thousands of rows is basically invisible on the webpage.

A static function can be used directly. The function does not take into account the large data volume in the clob area. You can use it as needed. /*** Extract the content of the clob field from the database and convert it to a string* @ Param Rs

1. Concepts To improve performance, you can use the following data access methods: A. Clusters B. Indexes -B-tree (normal or reverse key) -Bitmap -Function-based C. Index-organized tables D. materialized views The more layers the index has, the

1. Concepts DML transactions use row-level locks, and the query does not lock data. There are two lock modes: exlusive and share. Lock type: • DML or data locks: -Table-level locks (TM) -Row-level locks (TX) • DDL or dictionary locks A transaction

The concepts of incremental difference and incremental accumulation exist in RMAN Incremental backup, which were not well understood before. 1. Concepts Incremental difference: all changed data blocks since the backup of the backup level and

If odp.net is installed on your machine and you are sure that the machine is. config also has the following nodules: (64-bit +. in the. NET 4.0 environment, machine. the Config may have four copies, corresponding. check the 4.0-bit version of net2.0/

There is a seemingly Nb built-in function wm_concat in Oracle, which can easily implement the "Row-to-column" function (you can search for related usage and find a lot of information) Today I accidentally found a problem: In different Oracle

Recently, for a website project of the company, to call the Oracle database data of other systems (call center system), you can only connect to the query and create a stored procedure. Therefore, you can only use your brains on SQL statements to

Check the concept on the bus. The Oracle lock mechanism is somewhat different from MSSQL. Take the time to sit down and test it. Oracle uses the lock mechanism to provide data concurrency, consistency, and integrity between transactions. These

ArticleDirectory Restrictions on using the transfer tablespace: Starting from 11 GB, Oracle supports cross-platform table space transfer.View the list of supported platforms. If the endian format of the source and target databases is

SQL> Create tablespace fda1 datafile '/S01/APP/Oracle/oradata/db11g/fda01.dbf' size 50 m; tablespace created. SQL> Create flashback archive fla1 tablespace fda1 retention 1 month; flashback archive created. SQL> Col flashback_archive_name for a30sql>

1. Concepts The server first sorts the data in the memory area specified by sort_area_size. If the required space exceeds sort_area_size, the sorting is performed in the temporary tablespace. In dedicated server mode, the sorting space is in PGA,