DBA Wiz

An automatic failover is a switching role that causes the mirror server to take over the role of the principal server and bring its copy of the database online as the principal database. It involves high-safety mode and requires the presence of the mirror server and a witness server. The database should be synchronized and the witness must be associated to the mirror server. The job of the witness is to confirm whether a given partner server is up and operating. If the connection of the mirror server to the principal server is lost but the witness server is still connected to the principal server, the mirror server will not initiate a failover.

Failover clustering is a process in which more than one server is configured to host a single instance of SQL Server 2005/2008. The database will still be available if a server in the cluster fails. The cluster of servers contains shared disk that holds the data in the database. This type of configuration is also known as virtual server.

Database Publishing Wizard uses the following modes to deploy an SQL database:
Script mode: In this mode, Wizard generates a single SQL script file that a user can run manually on the target server for recreating the database schema and contents.
Web service mode: In this mode, Wizard connects to a Web host environment service and copies the content of a source database into a target database directly.

There are three types of database schemas, which are as follows:
Conceptual schema: It is also called a conceptual data model. It is a map of concepts and their relationships. It is used to describe the semantics of an organization.
Logical schema: It specifies problem domain in terms of a particular data management technology without being specific to a particular database management.
Physical schema: It is a term used in relation to data management. According to the ANSI four-schema architecture, it was the view of data that involved data management technology.

A database schema is the structure of a database. It is described in a formal language supported by the Database Management System (DBMS). It is a collection of database objects such as tables, views, sequences, synonyms, clusters, indexes, database links, procedures, functions, and packages. In a relational database, the database schema defines tables, fields, and relationships between the fields and tables. A database schema is stored in a data dictionary.

An external table is an efficient alternative to reading and loading flat files in a database. It can also execute queries in a flat file and it gives an impression of working with an Oracle table. It is primarily used to move data into and out of a database. It is considered as a convenient way to use SQL*Loader and Data Pump functionality. The external table does not exist in the database and can be of any format, and an access driver must be provided for the format of an external table. The disadvantage of using an external table is that the DML commands cannot be executed in an external table. An exception to this rule is the table creation DML statement. Another disadvantage is that an index cannot be created on an external table.

A job table is a scheduler object that is used to keep information pertaining to all the active jobs within a database. The information in a job table includes the owner of the job, the database objects referenced by the job, and the next run date. The statistical information, such as the number of times the job has run and the number of times the job has failed, is also stored in the job table. The job table also contains the STATUS column that holds the current state of a particular job, i.e., RUNNING, SCHEDULED, or BROKEN. Note: The *_SCHEDULER_JOBS view is used to view information stored in a job table.

Table is a base database object to store the database’s data or information. It is the foundation of every Relational Database Management System (RDBMS). Each database consists of one or more tables having their unique names. Each table consists of columns and rows. The table columns describe the data types and the table rows contain the actual data for the columns.

Database Publishing Wizard uses the following modes to deploy an SQL database:
Script mode: In this mode, Wizard generates a single SQL script file that a user can run manually on the target server for recreating the database schema and contents.
Web service mode: In this mode, Wizard connects to a Web host environment service and copies the content of a source database into a target database directly.