Basics Of Data Types and Database Objects

1. Which of the following is not supported by Oracle as an internal datatype? (Choose the best answer.)

CHAR

FLOAT

INTEGER

STRING

Oracle does not support the internal datatype "STRING." The other options, CHAR, FLOAT, and INTEGER, are all supported by Oracle as internal datatypes.

Explanation

Oracle does not support the internal datatype "STRING." The other options, CHAR, FLOAT, and INTEGER, are all supported by Oracle as internal datatypes.

2. Several object types share the same namespace and therefore cannot have the same name in the same schema. Which of the following object types is not in the same namespace as the others? (Choose the best answer.)

Index

PL/SQL stored procedure

Synonym

Table

View

Indexes, PL/SQL stored procedures, synonyms, tables, and views are all object types that exist within a schema. However, indexes are not in the same namespace as the others. Indexes are used to improve the performance of database queries by allowing for faster data retrieval. They are not directly related to the structure or definition of the data itself, unlike tables, views, and synonyms. Therefore, indexes have a separate namespace from the other object types mentioned.

Explanation

Indexes, PL/SQL stored procedures, synonyms, tables, and views are all object types that exist within a schema. However, indexes are not in the same namespace as the others. Indexes are used to improve the performance of database queries by allowing for faster data retrieval. They are not directly related to the structure or definition of the data itself, unlike tables, views, and synonyms. Therefore, indexes have a separate namespace from the other object types mentioned.

3. Which of these statements will fail because the table name is not legal? (Choose two answers.)

Create table "SELECT" (col1 date);

Create table "lower case" (col1 date);

Create table number1 (col1 date);

Create table update(col1 date);

Create table 1number(col1 date);

The table name "update" will fail because it is a reserved SQL keyword and cannot be used as a table name. The table name "1number" will also fail because it starts with a number, which is not allowed in SQL table names.

Explanation

The table name "update" will fail because it is a reserved SQL keyword and cannot be used as a table name. The table name "1number" will also fail because it starts with a number, which is not allowed in SQL table names.

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4. You need to record date/time values, with a precision of one second. What would be a suitable datatype for a single column to store this information? (Choose One that is most appropriate)

DATE

TIMESTAMP

DATE or TIMESTAMP

User Defined Data Type

A suitable datatype for recording date/time values with a precision of one second would be TIMESTAMP. The TIMESTAMP datatype allows for storing both date and time information, including seconds. DATE datatype only stores the date information without the time component. Therefore, TIMESTAMP is the most appropriate choice for this requirement.

Explanation

A suitable datatype for recording date/time values with a precision of one second would be TIMESTAMP. The TIMESTAMP datatype allows for storing both date and time information, including seconds. DATE datatype only stores the date information without the time component. Therefore, TIMESTAMP is the most appropriate choice for this requirement.

5. Which of the following constraints require an index? (Choose Two)

NOT NULL

PRIMARY KEY

CHECK

UNIQUE

The PRIMARY KEY constraint requires an index because it ensures that each value in the specified column(s) is unique and also serves as a unique identifier for each row in the table. An index is needed to efficiently enforce this constraint and allow for fast lookup and retrieval of data based on the primary key. Similarly, the UNIQUE constraint also requires an index to enforce the uniqueness of values in the specified column(s), allowing for efficient data retrieval and preventing duplicate entries.

Explanation

The PRIMARY KEY constraint requires an index because it ensures that each value in the specified column(s) is unique and also serves as a unique identifier for each row in the table. An index is needed to efficiently enforce this constraint and allow for fast lookup and retrieval of data based on the primary key. Similarly, the UNIQUE constraint also requires an index to enforce the uniqueness of values in the specified column(s), allowing for efficient data retrieval and preventing duplicate entries.

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