Which Three Statements Are True About Oracle Built-in Data Types?

1Z0-071 By islever Editorial Last updated

Columns and data types

Short answer

ADE CHAR defaults to length 1 when omitted, a CHAR column does not require an explicit length, and BLOB stores unstructured binary data in the database.

Question

Which three statements are true about built-in data types? (Choose three.)
  1. The default length for a CHAR column is always one character. Correct Answer
  2. A VARCHAR2 blank-pads column values only in the data stored is non-numeric and contains no special characters.
  3. A VARCHAR2 column definition does not require the length to be specified.
  4. A CHAR column definition does not require the length to be specified. Correct Answer
  5. A BLOB stores unstructured binary data within the database. Correct Answer

Key Takeaways

It tests whether you know that CHAR defaults to length 1 when omitted, and that VARCHAR2 requires an explicit length, while BLOB stores unstructured binary data.

This Oracle 1Z0-071 question tests knowledge of built-in data types, specifically CHAR, VARCHAR2, and BLOB behavior. The correct statements are A, D, and E, covering CHAR default length, optional length specification, and BLOB storage.

Common mistake: Many candidates incorrectly believe CHAR requires a length or that its default is always one byte, leading them to exclude A or D; others wrongly think VARCHAR2 length is optional.

Expert Analysis

Why the Answer Is Correct

  • A is correct: Oracle's CHAR data type defaults to a length of 1 when no size is specified. Although the default unit (BYTE or CHAR) depends on NLS_LENGTH_SEMANTICS, the length value is 1, making the statement true in the context of the exam.
  • D is correct: You can create a table with a CHAR column without specifying the length, e.g., CREATE TABLE tmp (col CHAR);. This is a valid Oracle DDL statement.
  • E is correct: BLOB (Binary Large Object) is designed to store unstructured binary data within the database, such as images or multimedia.
  • Together, A, D, and E are the three true statements among the given options.

Why the Other Options Are Wrong

  • B is false: VARCHAR2 columns are variable-length and do not blank-pad values; blank-padding is a behavior of CHAR, not VARCHAR2. The condition "only in the data stored is non-numeric..." is nonsensical.
  • C is false: A VARCHAR2 column definition requires an explicit length specification. For example, VARCHAR2 without a size throws ORA-00906: missing left parenthesis. So C is incorrect.
  • The suggested answer "AE" is incomplete; it omits D, which is also a true statement, and the question asks for three.

Community Comment Notes

  • As tom100men noted, "CHAR default is 1 byte, we can use: CREATE TABLE tmp (col CHAR);" and voted for D, E, F (though F is absent here).
  • bca123 argued that if D is correct then A should also be correct, highlighting the logical connection between omitting length and having a default.
  • 65e59ac confirmed, "Yes, you can create a table in ORACLE without specifying the length in CHAR column. D is right."
  • a947739 disagreed by stating you cannot, but Oracle documentation supports D.
  • ogi33 pointed out that NLS_LENGTH_SEMANTICS defines the length semantics, which explains why A's "always one character" can be debated.

Official Reference

https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/Data-Types.html

This link opens the official vendor documentation in a new tab.

Exam Strategy

For data type questions, memorize the defaults: CHAR defaults to 1 when size is omitted, VARCHAR2 requires a size, and BLOB/CLOB are for large objects. Watch for absolute words like "always" which often indicate a false statement.

Frequently Asked Questions

Why is option C incorrect for a VARCHAR2 column?

VARCHAR2 requires an explicit length in SQL; omitting it raises ORA-00906. Unlike CHAR, there is no default length for VARCHAR2.

Does CHAR default to 1 byte or 1 character?

The default length is 1, but the unit depends on NLS_LENGTH_SEMANTICS (BYTE by default, or CHAR if set). So it is not always one character.

More 1Z0-071 FAQ →

Discussion 6 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 6

  1. tom100men 👍 3
    DEF for me, CHAR default is 1 byte, we can use: CREATE TABLE tmp (col CHAR);
  2. ogi33 👍 1
    If you do not specify a qualifier, the value of the NLS_LENGTH_SEMANTICS parameter of the session creating the column defines the length semantics, unless the table belongs to the schema SYS, in which case the default semantics is BYTE.
  3. 65e59ac 👍 1
    Yes, you can create a table in ORACLE without specifying the length in CHAR column. D is right.
  4. a947739 👍 1
    you can't create a table in ORACLE without specifying the length in CHAR column
  5. bca123 👍 1
    But based on the scheme ans, id D is correct , then A should be correct!
Show 1 more comment
  1. billysunday1 👍 2
    Answer is A,E,F

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