Database usage-oracle bitmap index,-oracle bitmap Index

Database usage-oracle bitmap index,-oracle bitmap Index Currently, a large number of indexes are mainly B * Tree indexes. The index structure stores the rowids of key values and key values, which correspond one to one. Bitmap indexes are mainly

Use of the padding function lpad/rpad in oracle, lpadrpad

Use of the padding function lpad/rpad in oracle, lpadrpadLpad 1. Syntax Lpad (string, pad_length, [pad_str])2. ExplanationThis function indicates filling the specified character to the specified length from the left side of the string. The space of

Common Oracle functions-date functions, oracle date functions

Common Oracle functions-date functions, oracle date functions In the development and use of oracle, a variety of date functions are often used. The online date functions are searched for in batch, and there are many minor problems to use. I will

Mysql Installation and Use

Mysql Installation and Use In OJ, mysql is mainly used to store user information. It is easy to install and use. The following is a brief introduction. First, I will explain that my Linux branch environment is Ubuntu 12.04, and the general steps of

How to set the mysql root Password and mysqlroot Password

How to set the mysql root Password and mysqlroot PasswordHow to set the mysql root Password:1. The initial password for installing root for the first time is blank. Note that there is no password. Press enter to enterD: \ wamp \ bin \ mysql \ mysql5.

MySQL-10-mysql programming, linuxmysql Programming

MySQL-10-mysql programming, linuxmysql Programming MySQL Programming 1. Statement Terminator There are two default values:; and \ g (which can only be used in the command line) You can use the delimiter command to modify the statement Terminator,

MySQL-11-stored procedure, mysql Stored Procedure

MySQL-11-stored procedure, mysql Stored Procedure Stored Procedure The commonly used operating database language SQL statements must be compiled and then executed before execution. The Stored Procedure (Stored Procedure) is a set of SQL statements

Mysql foreign key Usage introduction, mysqlforeign

Mysql foreign key Usage introduction, mysqlforeign I. Basic Concepts 1. MySQL has the same definition of "key" and "Index", so foreign keys and primary keys are also an index. The difference is that MySQL will automatically index the primary keys of

MYSQL service cannot be started: InnoDB:. \ ibdata1 can & #39; t be opened in read-write mode, innodbibdata1

MYSQL service cannot be started: InnoDB:. \ ibdata1 can't be opened in read-write mode, innodbibdata1 I did an experiment there today and dumped the mysql database. Later I found that the service could not be started. The following error was

Oracle 11g replica uard creation in ORA-01665 resolution, dataguardora-01665

Oracle 11g replica uard creation in ORA-01665 resolution, dataguardora-01665Oracle 11g fails to restore the standby control file when creating data guard. When I mount standby database, tell me that the control file is not a standby control file and

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Left join, join, right join difference, leftjoin

Left join, join, right join difference, leftjoinLeft join returns records that include all records in the left table and join fields in the right table.Right join returns records that include all records in the right table and the joined fields in

Database trigger introduction and instance, database trigger instance

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Two forms of ORA-01502 oracle database index, ora-01502oracle

Two forms of ORA-01502 oracle database index, ora-01502oracle In the current project, when we run the batch, there is an SP always reports the error "ORA-01502: index 'wbill _ 102. PK_A_NOTWEB_ACT_PROVINCE_M 'or partition of such index is in

Problems with data import in different mysql versions: mysql version Data Import

Problems with data import in different mysql versions: mysql version Data Import The original mysql version is 3.4.10.1deb1, and the target mysql version is 5.0.51b-community-nt-log. The following error occurs during data import: 1. DELIMITER You

Database Stored Procedure introduction and instance, database Stored Procedure instance

Database Stored Procedure introduction and instance, database Stored Procedure instance I. Differences between stored procedures and functions: 1. In general, the functions implemented by stored procedures must be more complex, while the functions

Oracle performance optimization operation 12: Use Case statements to merge multiple scans, oraclecase

Oracle performance optimization operation 12: Use Case statements to merge multiple scans, oraclecase We often have to calculate different aggregation based on multiple sets of data tables. For example, the following example uses three independent

Oracle Performance Optimization Operation 14: using function-based indexes, oracle Performance Optimization

Oracle Performance Optimization Operation 14: using function-based indexes, oracle Performance Optimization As mentioned above, any operations on columns may cause full table scanning. For example: select * from emp where substr (ename, 1, 2) =

Oracle performance optimization operation 11: try to match the like clause at the front end. oracle clause

Oracle performance optimization operation 11: try to match the like clause at the front end. oracle clause Because the like parameter is frequently used, if the like clause can be indexed, the query efficiency will be greatly improved. Example:

MySQL series: innodb source code analysis-redo log structure, mysqlinnodb

MySQL series: innodb source code analysis-redo log structure, mysqlinnodb In innodb Engine implementation, a redo log system is built to ensure transaction persistence. Redo log is composed of two parts: the memory log buffer and the redo log file.

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