Oracle

-- Obtain the table primary key and typeSelect acc. column_name, ATC. data_typeFrom all_constraints AC, all_cons_columns ACC, all_tab_columns ATCWhere AC. table_name = upper ('table name ')And AC. constraint_type = 'P'And AC. constraint_name = acc.

Enable constraints: Enable (validate): Enable constraints, create indexes, and execute constraints on existing and new data. Enable novalidate: Enable constraints, create indexes, and only enforce constraints on new data, regardless of existing data

Let's first use a small table to explain which aspects should be paid attention to in the Oracle execution plan. HR @ orcl> set autotrace traceonlyhr @ orcl> select * from t; when fuzzy comparison of the two SQL statements, we recommend that you

(I) direct path loading and buffer cache Data inserted in the direct path is directly formatted as an oracle block from PGA without passing through the buffer cache. Then, a common ORACLE Server process writes data blocks to data files. Dbwn is not

(I) A table has many duplicate values in a column. The base is very small. What indexes should be created? -- Create a bitmap index. For details, see the comparison of the lock costs between B-tree indexes and bitmap indexes. For example: Create

This case takes China Construction Bank as an example.Download the created transaction table and name it ccb.txt.At this time, you have two options: sqlldr or external table   (I) sqlldrBecause online banking can only be used on win, if your OS is

Differences between Oracle database and MySQL database: 1. Group function usage rules In MySQL, group functions can be used at will in select statements. However, if a group function exists in a query statement in Oracle, other column names must

I encountered a lot of trouble when I recently used Oracle to import and export data! Then I carefully studied the Oracle database and summarized several command methods for import and export for future reference.Data export:1. Export the database

I have seen many people talking about issues such as TNS or the inability to log on to the database. I just summarized the following.First, the network structure of Oracle can be combined with encryption, LDAP, and so on .. We will not discuss it

1. View)1.1 conceptsView ----- is a "logical table \" defined by the SELECT query statement (which can be a single table or multi-Table query). Only definitions are defined without data, is a \ "virtual table \". when creating a view, you only save

Oracle may be the most widely used database in the world. At least in my projects, Oracle database applications account for half of the total. It can be said that in the past few decades, the front-end and business-layer technologies have changed,

What is checkpoint? A checkpoint is a database event that refreshes modified data from the cache to the disk and updates control files and data files. When does checkpoint occur? We know that the checkpoint will refresh the dirty data, but when

CREATE TABLE AREAS ( Radius number (5 ), Area number (14,2) ); Method 1: Use gotoDECLARE Pi constant number (9, seven): = 3.1415927; Radius INTEGER (5 ); Area NUMBER (14, 2 ); BEGIN Radius: = 0; LOOP Radius: = radius + 1; IF radius = 4 THEN GOTO

When using Qt to develop an Oracle program, the QOCI driver problem is often encountered, mainly because the following error occurs when the program is running. QOCI driver not loadedAvailable drivers: QSQLITE QODBC3 QODBC This indicates that Qt is

Connect to the Hibernate configuration file of the Oracle databaseThe Hibernate configuration file connected to Oracle has two formats: xml and Java attribute file. The codes of the configuration files in these two formats are given below. 1.

Because the original ASM shared disk capacity is small, archive logs and backup files cannot be installed. Therefore, we decided to add a disk. 1. Add a virtual disk to node 1 and place it in the original shared directory named asm4. Select SCSI and

SQL> alter database add logfile thread 1 group5 ('+ Data/myrac/onlinelog/myrac1_redolog_group5_01') size 100 m; SQL> alter database add logfile member '+ Data/myrac/onlinelog/myrackets redolog_group5_02' to group 5; SQL> alter database add logfile

EWEEK Labs/PC Labs can be said to be the leader in Benchmark Testing. As early as October 1993, their sister Magazine PC Magazine did the same test. This cooperation with PC Magazine has tested the performance of five types of databases on the Java

I have some experiences in using Oracle OLAP recently. Take a note: Oracle data warehouse has many implementation methods. I know two methods: One is ROLAP, which is based on fact table and dimension table. These tables are based on relational

Oracle, a famous software company, has achieved great success since it switched to the Linux platform in 2004. Oracle has now become the largest database software vendor on the Linux platform, and maintained a strong growth momentum. According to