Database Administrator

The syntax of the SELECT... for update statement is as follows:SELECT... for update [OF column_list] [WAIT n | NOWAIT] [skip locked];Where:The OF clause is used to specify the columns to be updated, that is, to lock specific columns on the row.The

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

The portable tablespace can now be migrated across platforms, making data publishing faster and easier. In addition, external table downloads make data transfer tasks easier and faster through conversion. How do you migrate data from one database to

System: Ubuntu 10.10 Mysql source file: mysql-5.5.8.tar.gz Install required tools: cmake, GNU make, gcc, Perl, libncurses5-dev, bison (optional), chkconfig Note:1. There are several bugs in the official source code from, which were manually modified

We recommend a very good CentOS 4.4 installation of the Oracle 10g system, which is of great learning value. Here I will mainly explain the application of installing the oracle 10g system, including introduction to the knowledge of installing the

Auto restart of Oracle Database and DDS software in Linux single-instance Environment 1. Modify/etc/oratab# Vi/etc/oratabOradb:/opt/ora10/product/10.2.0.1: Y (changed from N to Y) 2. Modify/etc/selinux/config# Vi/etc/selinux/configSELINUX = disabled

Run yum to check whether mysql has been installed on Fedora 13 and you do not want to uninstall it and reinstall it. Typing mysql directly does not respond. For details, refer to here. I don't know how to deal with it. Now let's look back.Step 1: #

This feature is required for projects. When I use navicat to set the date type to timestamp, I will find that IDE has one more option: View the SQL statements automatically generated by IDE: Write 'lastupdate' timestamp not null default '2017-00

1. Edit the/etc/my. cnf file and add "default-character-set = utf8" under "[client"2. Edit the/etc/my. cnf file and add "default-character-set = utf8" under "[mysqld"3. Restart the mysql service.# Sudo/etc/init. d/mysqld restart* View the system

I often see an hint/* + OPAQUE_TRANSFORM */In the AWR Report, which is inexplicable. Why? If you see this hint in AWR of database B, the reason is that other databases ACCESS database B through DB link, and access using insert into table_name select

I encountered an interesting situation that included InnoDB gap locks when I was troubleshooting deadlocks for a customer. In non-insert write operations WHERE a WHERE clause does not match any rows, I expect that the transaction will not have a

1. Open SQL Plus and enter the user name and password as prompted. Note: If you are a system user, you can only log on with sysdba. For example: sys as sysdba, enter the User password to log on. 2. After logon, create a tablespace. Here, my

Oracle 11g linux 32-bit client Configuration First, attach your own integrated client download link: Oracle 11g client Linux-32bit Download from FTP No. 1 of the customer's home: ------------------------------------------ Split line -----------------

Due to Oracle authorization problems, Maven3 does not provide Oracle JDBC driver. To Apply Oracle JDBC driver to Maven projects, you must manually add the driver to the local repository. 1. Obtain the Oracle JDBC Driver 1. Download the appropriate

What is the serial number in the Oracle database? Sometimes, when we add an index field to a new table (without any business functions), to ensure that the field value is unique during each data addition operation, you can create a sequence

CURDATE () or CURRENT_DATE () Returns the current date, in YYYY-MM-DD or YYYYMMDD format. Contains only the year, month, and day Select curdate () + 0; Result: 20140214 Select curdate () + 1; Result: 20140215 CURTIME () or CURRENT_TIME ()Returns the

Mysql5.6.15 forget the root password of the database:[Root @ oraserver139 ~] # Mysql-uroot-pEnter password:ERROR 1045 (28000): Access denied for user 'root' @ 'localhost' (using password: NO)View the currently installed mysql version:Root @

Test the use of the alter database backup controlfile to trace command to back up the Oracle10g Control File And restore the control file when the control file is lost-backup control file View the default path of alter database backup controlfile to

Set the database to start several dispatcher (start three dispatcher) SQL> alter system set dispatchers = '(protocol = tcp) (dispatchers = 3 )' Set the maximum number of dispatcher instances that can be started in the database at the same time

The binary log of Mysql records the information of all mysql database changes, so it is very important to the database. The role of binary log is summarized as follows: 1. It can be used for restoration of databases based on time points. 2. It can