Oracle

Step: 1. Choose File> reverse engineer> database... 2. In the pop-up window, select the relational database type. Here, use Oracle9i and click "OK. 3. Select using a data source in the new window and click the button at the end to select the data

The sdo_geom.sdo_buffer function is used for buffer query. It has three parameters: Param1: the geometric element to be queried. Param2: the geometric elements used for filtering. Param3: used to control the buffer radius value, buffer arc

(Length (TRIM (cbkssj) is nullThis statement should only be applicable to Oracle's strange situations. Should it be determined that length is equal to null ?! In addition to this, a strong SQL syntax is provided, which contains a lot of or and.

Sometimes we may need to filter the results of the query for repeated values. For example, we use the following SQL statement to query the results. Statement: Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.

Syntax Rules:Create [or replace] trigger [mode.] trigger name Before | after insert | Delete | (update of column name) On Table Name [For each row] When Condition PL/SQL Block Note: The meaning of for each row is that in a statement that operates a

Function is used to return specific data. During execution, you must find a variable to receive the return value of the function;Syntax: create or replace function function_name(Argu1 [mode1] datatype1,Argu2 [mode2] datatype2 ,........)Return

I. Oracle transaction control:1. A series of operations that constitute a single logical unit of work are called transactions.2. Database Transaction composition:1. 0 ~ Multiple DML statements2. One DDL (Data Define Language) Statement3. One DCL

-- PagingSelect * from (select t1.ename, rownum rn from (select * from emp) t1 where rownum = 6;   -- Develop a packageCreate or replace package tespackageType test_cursor is ref cursor;End tespackage; -- Paging Stored ProcedureCreate or replace

Rank, dense_rank, row_number, and group ranking partition Rank Dense_rank Row_number: the ranking adopts a unique sequence number continuous value, for example, 1, 2, 4 Partition: Limit the ranking to a group   Format: Row_number () over (partition

Thank you for choosing zhanghua first create. -- How to import dmp database files in oracle?　　Importing and exporting Oracle Data imp/exp is equivalent to restoring and backing up oracle data. The exp command can export data from the remote database

The table structure is as follows:   Field Type Col1 Varchar2 (64) Col2 Long   Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->-- Copy DataInsert into

Oracle Index Indexes and corresponding tables should be in different tablespaces. oracle can read data on different hard disks in parallel to avoid I/O conflicts. B-Tree Index: store the value and ROWID of the index field in the leaf node of B-tree.

Oracle has a wide variety of hint types, which can be roughly divided into the following categories:Optimization methods and objectives: such as RULE, CHOOSE, FIRST_ROWS, and ALL_ROWS.Access path: such as INDEX, FULL, CLUSTER, and INDEX_FFS.Query

Translation and sorting: Liu Xiaotao time: Abstract:This article describes the tablespace (the primary logical database structure of the Oracle database) and physical data files corresponding to each tablespace. For the convenience of introduction,

24.Use EXPLAIN PLANAnalyze SQLStatement   Explain plan is a good tool for analyzing SQL statements. It can even analyze statements without executing SQL statements. through analysis, we can know how ORACLE connects to the table, how to scan the

7.Reduce the number of database accesses When each SQL statement is executed, ORACLE performs a lot of internal work: parsing SQL statements, estimating index utilization, binding variables, and reading data blocks. it can be seen that reducing the

The most common Chinese Character Set ZHS16GBK (GBK 16-bit Simplified Chinese) supports traditional Chinese and stores one Chinese Character in length. The UTF8 character set is stored in multiple bytes. One Chinese character (simplified or

1. When connecting to the remote server from Oracle, you must install the client and overwrite the D: \ oracle \ product \ 10.2.0 \ db_1 \ NETWORK \ ADMIN \ tnsnames. ora file. If the connection fails, restart the OracleServiceORCL service. For

Such as the database name, database instance, SID ...... Oracle_SID SID is the abbreviation of System IDentifier (also known as Site IDentifier), and Oracle_SID is the abbreviation of Oracle System IDentifier. in Oracle, Oracle_SID appears in the

Several lock types and Related Parameters   The blocking mechanism is mainly used to control concurrent operations, block interference, and ensure data consistency and accuracy. There are three ways to block Oracle databases: Shared blocking,