Database Administrator

The period-over-period ratio is the nth month of the year and the nth month of the year, or the nth month of the year. Create a test table, which is assumed to be a sales quantity table: Create table t (dt date, cnt number ); Insert some test data.

1. view the size of all tablespaces SQL> select tablespace_name, sum (bytes)/1024/1024 M from dba_data_files group by tablespace_name; 2. Used tablespace sizeSQL> select tablespace_name, sum (bytes)/1024/1024 M from dba_free_space group by

During routine database maintenance, we need to check the invalid object information in the database in time and re-compile the abnormal object. For various object types, see the following compilation method: Check the name of the generated Invalid

During the top Shard, The PreparedStatement encountered garbled Characters During database storage, which had plagued the database for a long time and finally solved the problem. The problem code is as follows: Pstmt = con. prepareStatement

1) Background: Recently, an Oracle10g RAC dual-node experimental platform was built in vmware and oracle RAC was upgraded from 10.2.0.1 to 10.2.0.5. Later, it was found that the two linux systems often restarted automatically; 2) platform

1. Procedure for using a cursor (1) define a cursor Exec SQL DECLARE MY_CURSOR CURSOR ........ (2) Open the cursor Exec SQL OPEN MY_CURSOR; (3) read cursor Exec SQL FETCH MY_CURSOR INTO: MY_Stru; (4) Close the cursor Exec SQL CLOSE MY_CURSOR;

When we write SQL statements, we often ignore some details. The following is a summary of my own operations and materials. If there is something wrong or something wrong, hope to reply to me and learn from each other. Thank you!1. When a full table

MongoDB is a NoSQL database system. A database can contain multiple collections, each of which corresponds to tables in a relational database; A set of records identified by columns can be stored in each collection, and columns can be freely defined

When a table is accidentally deleted, hundreds of mb of data is lost? No. Now you don't have to worry about it. Oracle9i and above use a garbage collection solution, and it's easy to recover. No longer use precious time for database cloning/exp/imp

You can use the Change command to Change the string (that is, replace the string ). Syntax: C [HANGE] sepchar old [sepchar [new [sepchar] Sepchar is the separator, which can be "/" or "!" -- Special attention Old string New String For example,

The Table name and Schema name are the same: The schema and table names are both Arwen.Schema Arwen contains a PKG package with the Plus function. The result of adding two numbers is returned.SELECT Arwen. PKG. Plus (1, 2) FROM dual; -- no error

Now we are all-around. We have to be familiar with Oracle for Java. We need to test an application yesterday, so we need to have a database. We cannot test it in the production environment. So let us know over there, first, export the data of the

1. When LGWR is idle, it will check whether any data is written from redo buffer to redelog every 3 seconds. If yes, a background process will automatically write the data into it. 2. When a process needs to allocate space from the redo buffer, the

1.Function 1) Create a function Create or replace function get_tax (x number) Return number Begin Declare y number; Begin Y:=X-2000; If x= 0 then Return 0; End if; Returns y * 5/100; End; End

Use diagnostic file monitoring routinesI. Diagnostic filesDiagnostic files are a way to obtain information about database activities. They are used to solve database problems and contain information about important events in the database, these

MongoDB has three methods to save java objects. One is to implement the DBObject interface through a class, and the other is to use the object ing function of the spring-mongodb tool, converts a java object to the BSON document of MongoDB. One is to

In the database synchronization process, both the Database loading efficiency and the atomicity of each transaction in the database must be ensured, that is, the execution of Multiple SQL statements in a transaction must be successful for the above

About GoldenGateOracle Golden Gate is a log-based copy and backup software for structured data. It parses online logs of the source database or archive logs to obtain incremental data changes, apply these changes to the target database to

You can use the scott password triger, an existing Oracle account, to log in and use the existing table to perform the test. Create or replace procedure lpmtest2 As Para1 varchar2 (10); Cursor youbiao is select ename from test where sal>1300;

The most typical application of Database Synchronization is Remote Disaster Tolerance and the query statistics of the primary database. This is generally a one-to-one application. However, the demand for multi-dimensional synchronization sometimes