Oracle SQL

Which statement best describes the role of a primary key in a relational table?

• AIt stores descriptive text for the table
• BIt uniquely identifies each row in the table
• CIt automatically sorts rows alphabetically
• DIt prevents users from querying the table

Which statement returns every column from the EMPLOYEES table?

• ASELECT ALL FROM employees
• BSELECT * FROM employees
• CGET * FROM employees
• DDISPLAY employees.*

Which predicate returns rows where SALARY is from 3000 through 5000 inclusive?

• Asalary BETWEEN 3000 AND 5000
• Bsalary IN (3000 TO 5000)
• Csalary > 3000 AND < 5000
• Dsalary RANGE 3000,5000

Which function returns a character expression in uppercase?

• AINITCAP
• BLOWER
• CUPPER
• DROUND

Why is TO_DATE('2026-03-11', 'YYYY-MM-DD') usually safer than relying on implicit conversion?

• AIt is shorter to type
• BIt avoids dependence on session NLS date format settings
• CIt automatically commits the transaction
• DIt creates a permanent DATE column

What does an inner join return?

• AOnly unmatched rows from the left table
• BRows that satisfy the join condition in both tables
• CAll rows from both tables whether they match or not
• DOnly duplicate rows

Which set operator removes duplicates when combining two result sets?

• AUNION
• BUNION ALL
• CMINUS
• DINTERSECT ALL

Which function returns the number of rows, including rows where individual column values are NULL?

• ACOUNT(column_name)
• BCOUNT(*)
• CSUM(*)
• DAVG(*)

Which operator is most appropriate when a subquery is guaranteed to return a single value and you want exact equality?

• A=
• BIN
• CEXISTS
• DLIKE

Which statement inserts a new row into a table?

• AINSERT
• BALTER
• CGRANT
• DTRUNCATE

Which command is used to create a new table definition?

• AINSERT TABLE
• BCREATE TABLE
• CALTER TABLE
• DGRANT TABLE

What is a view in Oracle SQL?

• AA stored query that can be queried like a table
• BA physical copy of a table stored twice
• CA transaction control command
• DA type of sequence

What is the difference between a system privilege and an object privilege?

• ASystem privileges control actions in the database generally, while object privileges cont…
• BSystem privileges apply only to views, object privileges apply only to tables
• CThere is no difference in Oracle
• DObject privileges can be granted only by SYS

What is the main purpose of a foreign key constraint?

• ATo encrypt sensitive columns automatically
• BTo ensure that related child rows reference valid parent rows
• CTo speed up ORDER BY operations
• DTo convert a heap table into an index-organized table

Which clause must appear immediately after SELECT in a basic query?

• AThe list of columns or expressions to return
• BThe table name
• CThe WHERE keyword
• DThe ORDER BY keyword

Which condition correctly tests whether COMMISSION_PCT has no value?

• Acommission_pct = NULL
• Bcommission_pct == NULL
• Ccommission_pct IS NULL
• Dcommission_pct EQUALS NULL

Which function returns the number of characters in a string?

• AINSTR
• BLENGTH
• CMOD
• DSUBSTR

Which function converts a DATE to a formatted character string?

• ATO_NUMBER
• BTO_DATE
• CTO_CHAR
• DNVL

Why are table aliases commonly used in joins?

• ATo rename tables permanently in the data dictionary
• BTo shorten references and distinguish columns from different tables
• CTo force Oracle to create indexes
• DTo avoid writing the WHERE clause

Which set operator keeps duplicate rows when combining result sets?

• AUNION
• BUNION ALL
• CINTERSECT
• DMINUS

How does COUNT(commission_pct) differ from COUNT(*)?

• ACOUNT(commission_pct) counts only rows where COMMISSION_PCT is not NULL
• BCOUNT(commission_pct) counts more rows than COUNT(*)
• CCOUNT(commission_pct) returns salaries instead of counts
• DThere is no difference

If a subquery may return multiple rows, which operator is usually safer than = for exact matching?

• ABETWEEN
• BIN
• CTRUNC
• DIS

Why is it considered a best practice to list target columns explicitly in an INSERT statement?

• AIt makes the statement clearer and less dependent on table column order
• BOracle requires it for every INSERT
• CIt prevents all constraint violations automatically
• DIt converts the statement into MERGE

Which statement about Oracle DATE is correct?

• AOracle DATE stores only the year and month
• BOracle DATE stores both date and time information
• COracle DATE can be used only in PL/SQL
• DOracle DATE cannot be compared with SYSDATE

Which statement about a simple view is generally correct?

• AIt does not store table data itself in the same way a base table does
• BIt always stores a physical duplicate of every source row
• CIt cannot be queried with WHERE
• DIt must contain a GROUP BY clause

Which statement grants SELECT on HR.EMPLOYEES to user SCOTT?

• AGRANT SELECT ON hr.employees TO scott
• BALLOW SELECT FROM hr.employees TO scott
• CGIVE SELECT hr.employees scott
• DGRANT TABLE hr.employees SELECT scott

A department can have many employees, but each employee belongs to one department. How is this relationship usually modeled in a relational database?

• AStore EMPLOYEE_ID in the departments table
• BCreate a foreign key in the employees table that references departments
• CCreate no relationship because SQL can infer it
• DStore both tables in a single VARCHAR2 column

Which query fragment creates an alias with a space in it for the SALARY column?

• Asalary AS annual salary
• Bsalary "Annual Salary"
• Csalary AS "Annual Salary"
• Dsalary TO "Annual Salary"

Which pattern matches names that start with A and contain any number of additional characters?

• A'A_'
• B'A%'
• C'%A'
• D'[A]*'

Which function returns part of a character string beginning at a specific position?

• ASUBSTR
• BINITCAP
• CROUND
• DTRUNC

Which function converts a character value such as '1250' to a numeric value?

• ATO_CHAR
• BTO_NUMBER
• CTO_DATE
• DNULLIF

Which join type returns all matching rows plus unmatched rows from the left table?

• AINNER JOIN
• BLEFT OUTER JOIN
• CCROSS JOIN
• DSELF JOIN

Which set operator returns only rows that appear in both queries?

• AMINUS
• BUNION ALL
• CINTERSECT
• DOUTER JOIN

Which clause groups rows that share a common value so aggregate functions can be applied per group?

• AGROUP BY
• BORDER BY
• CWHERE
• DDISTINCT

What is a correlated subquery?

• AA subquery that references a column from the outer query
• BA subquery that can never be nested
• CA subquery that returns only one row
• DA subquery that uses no tables