Oracle SQL Interview Questions

by Kendba Admin / Apr 14, 2011 / Published in Sample Chapters
sql interview questions

Oracle DBA interview questions Answers during technical interview - A sample chapter:

A Sample Chapter of book Oracle DBA Interview Questions - Partial topic covered in this sample chapter is "SQL – Essential for Oracle DBA"

Here you can find out some Oracle Interview Questions and Answers for the topic of Oracle SQL and RDBMS. These all interview questions and answers are real time Oracle DBA interview questions and answers. Be careful about Oracle DBA interviews because sometime very strange SQL questions might be raised during interviews. As a Oracle DBA candidate you can’t eliminate the SQL interview questions during Oracle DBA interviews.

Some strange interview questions are really very simple but we found those strange because you are not aware of those questions and answers. Most of cases candidate failed due to not preparing proper interview questions and answers.

Following all Oracle DBA interview questions and answers are sampling from our excellent book “Oracle DBA Interview Questions and Answers”. These are only sample interview questions and answers of Oracle DBA book’s topic “SQL – Essential for Oracle DBA”. Full topic is covered in book with total 50 important and strange SQL interview questions with answers.

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Oracle SQL Interview Questions and Answers

Use the describe command or use the dbms_metadata.get_ddl package.

Fact tables and dimension tables. A fact table contains measurements while dimension tables will contain data that will help describe the fact tables.

If total number of rows are in EMP table 14 then we would get output 8 , up to 14 times.

Disable the foreign key constraint to the parent, drop the table, re-create the table, enable the foreign key constraint.

A Cartesian product is the result of an unrestricted join of two or more tables. The result set of a three table Cartesian product will have x * y * z number of rows where x, y, z correspond to the number of rows in each table involved in the join.

Default order is Ascending.

A Bitmap index.

Normal view is logical and only definition stored in data dictionary view of system schema means it doesn’t occupy any space in database, but materialized view is real table and it occupy space in database.

No A table has only one primary key.

Create one regular primary key column. And create NOT NULL column with Unique Constraints. Using this trick we can able to create more than one primary key in single table.

Yes. In the CHECK condition for a column of a table, we can reference some other column of the same table and thus enforce self referential integrity.

Yes we can insert NULL keys in cluster index and normal index.

Used by Oracle to store information about various physical and logical Oracle structures e.g. Tables, Tablespaces, datafiles, etc. Data Dictionary stores Oracle database metadata. We can retrive information from data dictionary.

Yes views are automatically updated if any base table updated.

SYSDATE is system function.

Alias is temporary and used with one query. Synonym is permanent and not used as alias.

Foreign key is the key i.e. attribute which refers to another table primary key. Reference key is the primary key of table referred by another table.

Yes we can delete, update, delete or insert in DUAL table as SYSTEM user. But it is very risky.

Output using database functions are becoming unstable and might be wrong or producing errors.

SQL commands are terminated using / or ; (semi-colon) but SQL*Plus commands are terminated using enter key.

No. SQL*Plus command never saved in buffer only SQL commands are saved in buffer.

No. We can't use LONG column in where clause or order by clause of query.

ROWNUM and ROWID are pseudo columns in table object in Oracle database.

ROWID has a physical significance i.e you can read a row if you know rowid. It is complete physical address of a row. While ROWNUM is temporary serial number allocated to each returned row during query execution.

Yes we can insert more than one NULL value in unique constraint or unique index. Because every NULL is not similar.

Yes we can create unique constraint or primary key using non-unique index.

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