Database Administrator

Import and export of Oracle databases The import and export of Oracle databases is an important technical activity, which not only solves the import and export of databases, but also facilitates and quick data access. Use imp and exp to import and

How Does Oracle Randomly Read values from a specific combination? Here, we will use the DBMS_RANDOM package and the case when statement as follows: 1. Use the DBMS_RANDOM.RANDOM function to randomly generate a value and then modulo the value. If we

Oracle Database Help The Oracle Database Help class encapsulates the methods used to connect to the Oracle database, which can be called on other pages without repeated writes. Import java. SQL. Connection;Import java. SQL. DriverManager;Import java.

Oracle SQL statement tracking 1. SQL statement tracking The execution of SQL statements must be performed on the Oracle server. The Oracle server detects and records all SQL statements executed by the access process. The commands used below are all

An error occurred while using create pfile form spfile In the RAC environment. I. Problem Solving 1. Check the parameter records in the normal RAC. Node spfile location SQL> show parameter pfile NAME TYPE VALUE ---------------------------------------

Common Oracle commands in Linux Common Oracle commands in Linux 1. Start the oracle database: // Switch to an Oracle user: [Root @ server36 ~] # Su-oracle // Enter the sqlplus environment. The nolog parameter indicates no Logon: [Oracle @ server36 ~]

Oracle filling tables with random data A script from AskTom can also fill in random data for a table. Create or replaceProcedure gen_data (p_tname in varchar2, p_records in number)-- This routine is designed to be installed ONCE pre database, hence--

SQL reads XML fields and sqlxml Fields Recently, we have to migrate data to an old system. This is a tough task. We need to compare the fields of the new and old data tables to migrate the data of the old system to the new system. Although the data

[Instance] in php, the PDO method is used to add, delete, modify, and query databases.You can easily organize and understand the PDO operation instances. Note that you need to enable the pdo support for php. php5.1 and later versions support

Improves SQL query efficiency and SQL Efficiency1. To optimize the query, try to avoid full table scanning. First, consider creating an index on the columns involved in where and order. 2. Try to avoid null value determination on the field in the

Mysql trigger, mysql trigger instance Trigger 1. Definition: a specific operation is triggered by insert, update, delete, and other events. The trigger can trigger multiple execution statements. Note: triggers cannot contain keywords such as start

Misunderstanding of Oracle Parallel 2 -- actually locking the entire table, oracle2 -- I have written a misunderstanding about Oracle parallelism before. 1. In fact, you didn't use parallelism. I always thought that Oracle would only lock the data

1022, hp1022Today, I used powerdesigner to modify some foreign key relationships. The names of the two foreign keys are the same and I forgot to change them. Then, when running the SQL file with navicat, the error [Err] 1022-Can't write; duplicate

View MySQL indexes and mysql IndexesMysql> show index from tblname; mysql> show keys from tblname; · Table name. · Non_unique: 0 if the index cannot contain duplicate words. If yes, it is 1. · Key_name index name. · Column serial number in

MySQL database: consolidate the DDL statements, mysqlddl The SQL language includes four major programming languages: Data Definition Language (DDL), data operation language (DML), Data Control Language (DCL), and transaction control language. Data

Oracle uses AWR's SQL ordered by Gets and SQL ordered by Reads to diagnose problems. awrreads I have read many database reports before, and have encountered two serious performance problems recently. They are very representative, so I recorded them.

Oracle sys_context () function, oraclesys_context The first parameter is 'userenv', which is fixed. The second parameter is also fixed, but multiple options are fixed. The optional values are as follows: Select sys_context ('userenv',

Mongodb study notes, mongodb Summary of Mongodb study notes over the past few days /*** Get login client * @ author xuyw * @ email xyw10000@163.com * @ param host * @ param port * @ return */public static login client getlogin client (String host,

MySQL study note _ 3_MySQL create a data table (medium) and study note _ 3_mysqlCreating a data table in MySQL 3. Data field attributes 1. unsigned [unsigned] Space can be doubled, for example,-128 ~ 127 increase to 0 ~ 255 Note: Only numeric fields

Mysql partition, mysql table Partition I. Functions of mysql partitions Ii. Mysql partitioning Methods Iii. Mysql partition implementation Master-slave Problems1. Database Backup (Master/Slave database) 2. database load balancing