Database Administrator

Oracle Database Advanced subquery Oracle Database Advanced subquery ① SubqueryA subquery is another SELECT statement nested in an SQL statement.Subquery (internal query) is executed before the master query is executed.Main query (external query)

Oracle analysis function PERCENTILE_CONT Query the salaries of people with the salary distribution of 25%, 50%, and 75% in each department. percent_rank () is the relative position in the ranking. Create table EMP(Empno number (4) not null,ENAME

Modify the Oracle Job sched Log Level and delete the running log Oracle jobs that have been running for a long time will generate a large number of running logs, which can be cleared through the following methods: 1. Create a job: Create job links

When the Oracle Session is locked A problem often occurs. A table in Oracle cannot be updated suddenly, either through pl/SQL Developer or through sqlplus, the execution of the update statement or the execution of the select * from table_name for

Oracle uses handles for non-Backup Recovery in specific scenarios In dba's work, backup is the foundation of all work. If there is no backup, it would be difficult to recover the data easily. If the business data requirements are high, resulting in

Notes for Oracle control file multiplexingBecause the control file is very important to the database, the control file is usually reused after the dbca database is created. For example, in Oracle10g, three control files are generated by default and

ORA-30009: connect by memory insufficient Today in the Oracle 11G environment manufacturing data encountered ORA-30009: connect by Operation memory is insufficient, 10g began to support XML, changed to xmltable can be. SQL> drop table t_range purge;

Oracle forced index using HINT, oraclehint First of all, it depends on whether your Oracle optimizer uses RBO or CBO,(1) If RBO is used, it will be performed in the Rule Order.(2) If CBO is used, you can use the HINT method to modify it.

Step-by-step introduction to databasesDatabase Table A database usually contains one or more tables. Each table is identified by a name (for example, "customer" or "order "). A table contains records (rows) with data ). The following example shows a

Enable mysql remote connection in Linux and mysql in linux Procedure for enabling mysql remote connection in Linux.Mysql remote connection linuxserviceserveruserMysql by default, the root user can only access the local database, but cannot remotely

High-efficiency frequent mode mining algorithm PrePost and fin c ++ source code, prepostfin For the C ++ source code of PrePost, see http://www.cis.pku.edu.cn/faculty/system/dengzhihong/source%20code/prepost.cpp.For details about the Algorithm, see

SQL _wm_concat function experiment: implement field merging, SQL _wm_concat Field Original Works are from the blog of "Deep Blue blog". You are welcome to reprint them. Please note the following source when reprinting them. Otherwise, you will be

Mysql binary log file error causes mysql service to fail to start. I opened phpmyadmin today and found that I couldn't connect to the mysql database. I couldn't restart mysql and found the following error when I checked the log. mysqld: File

Oracle locks the statistics of temporary tables and whether the hint and oraclehint can be dynamically collected after the lock The statistical information of the global temporary table cannot be collected. If it is collected, its statistical

Big data backup and recovery application case-Using Partitioned Tables to back up and restore Data Big data backup and recovery application case-back up and restore data through a partitioned table Massive Data backup and recovery Solutions The

MYSQL installation error "conflicts with file from package mysql-libs-*" solution, mysqllibs When installing MYSQL: Error: [root@localhost opt]# rpm -ivh MySQL-server-5.5.32-1.el6.x86_64.rpm Preparing... #############################

The "APPLY security settings error" solution appears during MySQL installation. mysqlapply **************************************** ****************************************************** Original works, from the "Xiaofeng residual month xj" blog,

For troubleshooting mybatis concurrency, refer to hibernate and mybatishibernate. A typical example is that two bank operators operate on the same account at the same time. For example, IF operator A and operator B read an account with A balance

ORA-27154 cannot start database due to semaphore problem, ora-27154 Database Prompt (11.2.0.1) when the Test Library executes startup ): Error querying ORA-27154: Error: ORA-27154Text: post/wait create failed --------------------------

Step-by-step explanation of ORACLE (Lecture 2), lecture 2 of oracle1. Common ORACLE Data Types (not commonly used for other types) (1) character type 1. char fixed length, up to 2000 characters. For example, put the first four characters of char (10)