create index

First, Index: (1) Unique index: When the CREATE INDEX statement is invoked, a unique index is created with the unique option.(2) composite index: The combination of two or more columns in one table is indexed, the maximum number of columns for a

* * The test is for the next test, according to the condition of the increment column as the partitioning condition, according to the time as the partition condition. Create tablespace test01 datafile ' D:\oracle\oradata\myora\test01.dbf ' size

The server transaction log (Transaction logs) is a very important but often overlooked part of the database structure. Because it is not as active as the schema in the database, few people are concerned about the transaction log. The transaction log

First look at the SQL syntax DB2 provides query language SQL (Structured query Language) of the related database, which is a very colloquial, easy to learn and understandable syntax. This language is almost always required by every database system

I've often seen people ask this question, I've set up multiple indexes on the same table, why does Oracle choose one at a time and not use multiple indexes at the same time? Generally speaking, the common access to the same table more than two

Data is indexed in SQL To index a table, start the ISQL/W program in the taskbar SQL Sever program group. After entering the query window, enter the following statement: CREATE INDEX Mycolumn_index on MyTable (myclumn) This statement establishes

Recently, because the company needs, fuzzy search for similar keywords, so directly consider the use of Lucene. Lucene allows you to add search functionality to your program, and Lucene can index and search the data you parse from the text, and

A brief introduction to the characteristics of OLTP and OLAP systems A: OLTP and OLAP are the 2 most commonly used systems in our daily production libraries, and simply say that OLTP is a system based on a multiple transaction short time slice, and

Data | Database MySQL time is not long, the operation of the database is nothing more than the increase of records, find records delete records and modify records. Summed up some of the following commands to share with you: Connection command: mysql-

oracle| Data | database In an Oracle database management system, you assign a table space (tablespace) when you create a library table (table), and if you do not specify Tablespace, use the tablespace of the system user. We may encounter such

(1) Data definition language (DDL) The data definition language is used to define the database's level patterns. Common keywords are: Create (create data table), alter (change datasheet), drop (delete datasheet). Set up a data table CREATE TABLE

When diagnosing a problem with a lock, check with the holder, the person who is blocked. Often is very troublesome, if you do not accumulate the script, rely on Manual Check to check a lot of tables, such as V$lock,v$process p, v$session s,

Although indexes are not always faster than full table scans, many times we want Oracle to use indexes to execute certain SQL, at which point we can force SQL to use index through the index hints. The format of the Index hints is as follows: /*+

The integrity of the data is used to ensure that database data follows specific business rules. In an Oracle database, you can use constraints, triggers, and application code (procedures, functions) to achieve data integrity in 3 ways. Today we

I. Data definition DDL (data definition Language) Data-setting language refers to the language defined in the format and form of data, he is the first to be set up when each database is to be established, what is the form of data, the form of a

oracle| Data | database | performance Oracle database is favored by more and more enterprises because of its high reliability, security and compatibility. How to keep Oracle databases in good performance is a concern for many database administrators

SQL Syntax | reference | Grammar reference one, data definition DDL (data definition Language) Data-setting language refers to the language defined in the format and form of data, he is the first to be set up when each database is to be established,

  Image upload is a very common feature in the website. Thinkphp also has its own picture upload Class (UploadFile.class.php) and Picture model Class (Image.class.php). Convenient for us to implement the image upload function, the following is the

Because the work needs, the need to use PHP to achieve a large number of Web site full text search, and the most popular Full-text search engine library is Lucene, it is a subproject of Apache Jakarta, and provides a simple and practical API, with

Now explain what "high water level" is: Logical storage structure of Oracle: Tablespace--> segment--> Area--> block Block: is the smallest storage unit, now the standard block size is 8k,oracle every I/O operation is also done by block, that is,