Question:- There are many databases available in the market. The commonly used databases are Oracle, IBM db2, Microsoft SQL Server, Microsoft Access, MySQL and SQLite, PostgreSQL, MariaDB.
Answer:- Below 5 are the physical components of Oracle Database: Data files Control files Redo log files Password files Parameter files
Question:- What are the roles of DBA?
Answer:- A DBA has the authority to create new users, remove the existing users, or modify any of the environment variables or privileges assigned to other users. • Manage database storage • Administer users and security • Manage schema objects • Monitor and manage database performance • Perform backup and recovery • Schedule and automate jobs
Question:- What are the different Oracle Database objects?
Answer:- Tables Views Indexes Synonyms Sequences Tablespaces
Question:- What is a Synonym in Oracle terminology?
Answer:- A synonym which is also known as an alias is an identifier that can be used to reference another database object in a SQL statement. A table, view, sequence are the types of database objects that can be created for a synonym.
Question:- Explain the types of Synonyms?
Answer:- There are two types of Synonyms which are- Public and Private. A public synonym isn’t part of any schema. A public synonym is one that can be used by any database user. A private synonym does belong to a specific schema. In other words, when only the owner can access it, it is called a private synonym.
Question:- What are the types of backups in Oracle?
Answer:- The main four types of backups in Oracle are: (ⅰ) COLD Backup (ⅱ) HOT Backup (ⅲ) Import – Export Backup (ⅳ) RMAN Backup
Question:- What are Hot Backup and Cold Backup?
Answer:- Hot backup is also recognized as an Online Backup because here the backup is taken while the database is active and running. And when the backup can only happen while the database is in shut down mode then it is called Cold Backup which can also be identified as Offline Backup.
Question:- What is the password file and why it is needed?
Answer:- Database users’ passwords are stored in the database’s data dictionary. When a user attempts to log into the database, the user’s usernames and passwords are compared to the values contained in the database. The user is given database access only if the username and password match. The data dictionary is stored in the database and can be accessed as long as the database is available. The dictionary also contains the passwords for the administrators. The data dictionary would be unavailable until the database is locked. Since starting up a down database is one of the administrator’s jobs, there needs to be a way for them to log in even if the database is locked. That’s where the password file comes into the picture. A password file is an operating system file that is held on a separate disc from the database. It stores the username and password for users with the SYSDBA or SYSOPER privileges. And when the database is down, administrators with certain privileges are authenticated using the password files.
Question:- What are datafiles?
Answer:- All the tables are stored in data files. The data file has all the data stored. The data files hold all the database data. The data of relational database structures, such as tables and indexes, is bodily stored in the data files owed for a database
Question:- How do you switch from an init.ora file to a spfile?
Answer:- To switch from an init.ora file to a spfile, we should create spfile from pfile command then shutdown instance and startup once again
Question:- What are the different types of SQL statements?
Answer:- The five type of SQL statements are: 1. Data Definition Language 2. Data Manipulation Language 3. Transactional control 4. Session Control 5. System Control
Question:- What is Data Normalization?
Answer:- The process of arranging data in a database is known as normalization. This involves building tables and defining relationships between them according to rules designed to protect data while also allowing the database to be more flexible by removing redundancy and conflicting dependencies.
Question:- What is a control file?
Answer:- A binary file that records the physical structure of the database and is required to start and run the database. A control file contains information such as • Data file • Database name • Redo file name • Locations of associated data files and redo files. • Timestamp of database creation. • Current log sequence number • Checkpoint information
Question:- A binary file that records the physical structure of the database and is required to start and run the database. A control file contains information such as • Data file • Database name • Redo file name • Locations of associated data files and redo files. • Timestamp of database creation. • Current log sequence number • Checkpoint information
Answer:- Steps to recover a lost control file are: 1. Start the database in the NOMOUNT mode 2. Create the control file from the control file backup with CREATE CONTROLFILE statement, and place it in the correct location. 3. Mount the database 4. Recover the database 5. Open the database
