Database Administrator

CHAR to NUMBER:Use the TO_NUMBER function to convert characters to numbers, for example:V_total: = TO_NUMBER ('192. 0') + sal;-15-16BytesNUMBER to CHAR:The TO_CHAR function can be used to convert numbers to characters, for example:V_comm: = TO_CHAR (

The distinct keyword filters out redundant duplicate records and retains only one record. However, it is often used to return the number of records that do not record duplication, rather than returning all values that do not record duplication. The

Because the data in many large tables is deleted in the project, the log-free method is adopted at first, and then the integration test shows that if there is an interruption during the delete process, in this case, the table can no longer be used.

1. final_url after END is an alias 2. UTL_URL.unescape (final_url, 'utf-8') is the decoded url. 3. At the beginning of Oracle10g, the database has built-in regular expressions that comply with the ieee posix (Portable Operating System for Unix)

133 export the database elink: dbexport-o/home/ap/dcclink/. shan/194/elink; 132 import the database elink: dpimport-c-ddatadbs-I/home/ap/dcclink/. shan/elinkelink.   The problem is as follows: 1. The type of your terminal is unknownto the

When importing the attachment table AFFIX, the data volume is more than items, but AFFIX has a large blob field, which makes the query very slow, the network in the working environment is very unstable. I started to import it for about half.

Oracle-view, sequence and Index Goal: Learn to use view sequences and indexes! I. View: A) create a view: Create ViewView nameAsSQL statement; Extended: When you need to change the column name-- Create view name (column name 1, column name 2,...

For a long time, masters have told us that Oracle's NULL and 0 are different. What is the difference. When I practiced it, I forgot the warnings. Yesterday I made a report. The customer said how to add the details differently from the value of the

Data Table connections include:1. Inner join (natural join): Only the rows matching the two tables can appear in the result set.2. external connections: including(1) left Outer Join (the table on the left is not restricted)(2) Right Outer Join (the

Hibernate helper class (officially recommended) Public class HibernateUtil { Private static final SessionFactorySessionFactory=BuildSessionFactory(); Private static SessionFactory buildSessionFactory (){ Try { // Create the SessionFactory from

1. When writing a query statement, make sure that the Java type matches the database type. If not matched, the query efficiency may be affected. For example: 2 when writing an insert statement, if the target field may be blank, you can use the

1. create two new log groupsAlter database add logfile group 4 ('d:/Oracle/ORADATA/ORADB/REDO04_1.LOG ') size 1024 k;Alter database add logfile group 5 ('d:/ORACLE/ORADATA/ORADB/REDO05_1.LOG ') size 1024 k;　　2. Switch the current log to a new log

In MongoDB1.6, it is easy to add members to the Replica Set as follows: # Add new membersRs. add ("192.168.95.210: 10000 ");# Add new elected membersRs. addArb ("192.168.95.216: 10001 "); With this configuration, Mongo automatically synchronizes

Oracle controls the connection of ip addresses (we can also use database triggers to record user logon conditions, but cannot record users with dba permissions), simply set allowed IP addresses and prohibited IP addresses, before oracle9i, there was

When we used to display the database query results on the page, we always had to judge the null field. If it was null, it would display "". Suddenly we found this method stupid, in addition, "null" appears on the page ". When using the Oracle

Recently, I found several random SQL queries in mysql on the Internet. I recorded the results.SELECT * FROM uchome_mtag AS a JOIN (select max (tagid) AS id FROM uchome_mtag) AS BON (a. tagid> = FLOOR (B. id * RAND () LIMIT 50I found a problem after

1. Add clusterware nodes On an existing Node Cluvfy stage-pre nodeadd-n node3 [-fixup [-fixupdir fixup_dir] [-verbose] -- A BUG occurs during installation of 11.2.0.2, and shared disk detection is always unsuccessful. Therefore, check that only

Implementation of the stored procedure for the Oracle large table replication solution: ProcedureMakePayPlayIraBakNewIs V_num number; Begin Vanceinfo. gmac_log_pro.setloginfo ('Makepayplayirabaknew', '123', '9', Sysdate,

Use mysqldump + crond for backup Create a database backup sh file such as/root/sbin/db-backup.sh DATE = 'date + % Y-% m-% d' /Usr/bin/mysqldump-uroot-p123456 mydatabase>/root/backup/mysql-backup. SQL. $ DATE Contents are all tables in the backup

Manual database creation is a common situation for DBAs because GUI environments cannot be provided in some cases. In fact, it is very convenient to set relevant parameters or values for manual database creation. This document describes the steps