Most Recent Oracle 1Z0-071 Exam Questions & Answers

Single-row functions in SQL return one result per row, and the following statements are true:

A: The data type of the returned value can indeed be different from the data type of the argument provided to the function. For example, the TO_CHAR function can take a numeric input and return a character string.

B: Single-row functions can be nested within each other to any level that is supported by Oracle. This means you can have a function call as an argument to another function, and so on.

E: The argument to a single-row function can be a column name, a variable, a literal, or an expression. This flexibility allows these functions to be very powerful in SQL expressions.

The incorrect options are:

C: Single-row functions do not return a single result row per table; they return a result for each row that is processed.

D: They are not limited to accepting only one argument. Some functions, like NVL, accept multiple arguments.

F: They are not limited to use in the WHERE clause; single-row functions can be used in any part of a SQL statement, including SELECT and ORDER BY clauses.

Oracle Documentation on Single-Row Functions: SQL Functions

The statement is trying to create a table with columns of different data types and constraints. Here's what needs to be corrected:

C: In Oracle, the LONG data type is used for character data of variable length up to 2 Gigabytes, but it is deprecated, and you should use CLOB or VARCHAR2 instead. Furthermore, a table cannot have more than one LONG column.

D: The NOT NULL constraint should be specified at the column level, not at the table level. The correct syntax for creating a table with a NOT NULL constraint is to define it inline with the column definition, like this:

ename VARCHAR2(15) CONSTRAINT ename_nn NOT NULL,

The other options are incorrect:

A: The foreign key constraint syntax is correct; the word CONSTRAINT is followed by the constraint name and then the REFERENCES clause.

B: The foreign key constraint can be defined at the column level.

E: While it's a good practice to name constraints, it is not mandatory for the primary key constraint to have a name; Oracle will generate one if it's not provided.

Oracle Documentation on CREATE TABLE: SQL Language Reference - CREATE TABLE

Oracle Documentation on Data Types: SQL Language Reference - Data Types

About the roles and behavior of subqueries in SQL:

A . A subquery can be used in a WHERE clause: Subqueries are often used in WHERE clauses to filter rows based on a condition evaluated against a set of returned values.

B . A subquery can be used in a HAVING clause: Similar to WHERE, subqueries can be used in HAVING clauses to filter groups based on aggregate conditions.

D . <ANY returns true if the argument is less than the highest value returned by the subquery: The <ANY (or <SOME) operator compares a value to each value returned by a subquery and returns true if the comparison is true for any one of the returned values.

Incorrect options:

C: =ANY evaluates true if the argument matches any single value returned by the subquery, irrespective of the number of values.

E: A subquery can indeed be used in a FROM clause, known as a derived table or inline view.

F: <ANY returns true if the argument is less than any of the values returned by the subquery, not necessarily the lowest.

G: A subquery can be used in a SELECT list, particularly when the subquery is designed to return a single value (scalar subquery).

A . True. The DECODE function can evaluate conditions, but it is limited to equality checks. On the other hand, CASE can evaluate these and a broader range of conditions using different comparison operators.

D . True. DECODE is a function in Oracle SQL that allows for simple conditional query transformation. CASE is not a function but a statement that provides more flexibility and readability when handling conditional logic in SQL queries.

DECODE is more limited compared to CASE since it can't perform logical operations other than equality.

A: True. A full outer join does indeed return both matched and unmatched rows from both tables involved in the join. It combines the results of both left and right outer joins.

E: True. An inner join, by definition, returns rows that have matching values in both tables. Rows from both tables that do not match are not returned in an inner join result set.

Inner joins match rows from the joined tables based on the join condition, while outer joins include all rows from one or both tables regardless of whether a matching row exists in the other table.

Reference: The Oracle SQL documentation explains different types of joins, including inner joins, left and right outer joins, and full outer joins, clarifying how they differ in the result sets they produce.