Database Administrator

The following describes how to use common data dictionaries for Oracle users by category. I. Users View the default tablespace of the current user SQL> SELECT username, default_tablespace FROM user_users; View the role of the current user SQL>

Nested SELECT statements are also called subqueries, for example: SELECT name FROM bbc WHERE region = (SELECT region FROM bbc WHERE name = 'Brazil ') The query result of one SELECT statement can be used as the input value of another statement. The

Paging browsing is a common Web application function. For MySQL databases, you can easily use limit statements to implement paging. for SQL Server databases, A common method is to use the cursor of the dataset to implement paging. This method is no

Why View A view is a convenient method. It only gives users access to a part of a table. The view can restrict the returned records and available fields. Therefore, users are authorized to access this view rather than the table itself to restrict

Explain shows how mysql uses indexes to process select statements and connect tables. It can help you select better indexes and write more optimized query statements. You can add the explain statement before the select statement: For example:

Introduction Let's skip the concepts, steps, and syntax of the cursor. Let's look at an example: Table 1 OriginSalary Table 2 AddSalary There are now two tables, one of which is OriginSalary table-payroll, with three fields: 0_ID employee id

I actually saw the 50 things that Robert Treat had sorted out on the same day, "50 things that I need to know before migrating Mysql to Oracle" and 50 things I need to know before migrating Oracle to Mysql., it's just that this list of Baron

Recently, I encountered the problem of "how to connect SQL to remote MySQL", and now the problem is finally solved. I posted the method: (my operating system is Win7, and the database is SQL2005 .) 1. Install the mysql odbc driver on the SQL SERVER;

NOR and NAND NOR and NAND are both Flash technologies. NOR is developed by Intel. It is a bit similar to memory and allows direct access to any memory unit through an address. Its disadvantage is low density and low capacity ), writing and erasure

Recently, I accidentally talked to a customer about an interesting Service Pack problem. The IT team decided to apply SP2 to its SQL Server production Server. They perform their due diligence: first apply the Service Pack to the Server in the test

The new version can bring more efficient technology to the software. Now we can forget five aspects of the Oracle database. 1. only DBA can restore Data People who work directly with SQL database-DBAs and IT information personnel can cause database

Before Oracle9i appears, you can only export and import tables to redefine them. Therefore, table redefinition is an offline process. Even an online change to "alter table add NEW_COL NUMBER (3)") will lead to an exclusive locks deadlock. This

We know that the role permissions of users are not available in the stored procedure. For example: SQL> select * from dba_role_privs where grantee = 'suk ';GRANTEE GRANTED_ROLE ADMIN_OPTION DEFAULT_ROLE------------------------SUK DBA NO

Unlike automatic database backup, the system administrator must take certain actions to protect data from unauthorized users. If you are using MySQL, you can use some convenient functions to protect the system and greatly reduce the risk of

Preface In a single application environment or system with relatively simple business, the bottleneck of system performance problems is often self-evident. The premise for solving the problem is that locating the problem is easier to solve, however,

Oracle databases are widely used in various fields of society, especially in the Client/Server mode. However, application developers often encounter the problem that the performance of the entire system decreases significantly as the data volume

Oracle databases store a variety of data, some of which will become larger over time. Such as dating chat logs, SMS sending and receiving logs, production system logs, dynamic website publishing system logs, and so on. This information is closely

Q:We transplanted our Oracle database to the new environment. Some customer tables exist in two databases at the same time, but those tables in the new environment have some additional fields. Can you help me use the import/export tool? In this way,

1. Start and close the database 1) Start the database $ SvrmgrlSVRMGR> connect internal (instance startup)SVRMGR> startup 2) shut down the database $ svrmgrlSVRMGR> connect internalSVRMGR> shutdown [immediate/abort]

To prevent others from accessing the database from external sources and steal other important information such as the user name, password, and credit card number in the database, when we create a database-driven solution, the first design decision