The Oracle ROLLBACK statement makes all changes since the last COMMIT permanent.
Answer: B
Correct answer: False
ROLLBACK does the opposite, discarding every uncommitted change and restoring the data to its state at the last COMMIT. It is COMMIT that makes changes permanent and visible to other sessions.
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You have linked SQL*Plus to an external text editor. To invoke the text editor for use within SQL*Plus, which command do you use?
Answer: D
Correct answer: Edit [ FileName ]
The EDIT command opens the external editor that has been defined for SQL*Plus, either on the named file or on the current buffer. The name of the editor itself is never typed as a command; it is set once with DEFINE _EDITOR, and EDIT then invokes whatever was set.
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An Oracle System Change Number (SCN):
Answer: D
Correct answer: is a value that is incremented whenever database changes are made.
The system change number is a database-wide counter advanced whenever a change is committed, and it stamps every change in the redo stream and every datafile header. It is what allows Oracle to establish the ordering of changes, to determine whether a set of files is consistent, and to recover to a chosen point in time.
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Which of the following is not true of SQL views?
Answer: A
Correct answer: Oracle views cannot use the ORDER BY clause in view definitions.
This is the statement that is not true, and it is the one place where Oracle departs from the standard in the permissive direction. SQL-92 forbids ORDER BY in a view definition, on the ground that a view is a relation and a relation has no order; Oracle allows it, which is convenient and is the exception the item is testing.
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When using SQL*Plus, Oracle commands, column names, table names and all other database elements:
Answer: A
Correct answer: are case insensitive.
SQL keywords, table names, column names and other identifiers are matched without regard to case, so SELECT, select and Select are the same, as are CUSTOMER and customer. Case matters only inside quoted string literals, where the characters are data, and in identifiers deliberately created within double quotes.
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Which of the following is not true about modifying table columns?
Answer: D
Correct answer: You cannot increase or decrease the number of decimal places.
This is the statement that is untrue: the scale of a numeric column can be altered, subject to the existing data fitting. The other three hold - a column may be dropped, a column may be added provided it allows nulls or a default is supplied, and character length and numeric precision may be increased freely.
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When you type Start FILENAME, the statement in your file will be executed automatically.
Answer: A
Correct answer: True
START filename, and its abbreviation @filename, reads the file and executes the statements in it one after another as though they had been typed. This is how scripts are run, and the assumed .sql extension means the name is usually given without one.
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In SQL*Plus, the DESCRIBE command displays the structure of a table.
Answer: A
Correct answer: True
DESCRIBE, commonly abbreviated to DESC, lists a table’s columns with their data types and whether each accepts nulls. It reports the definition only and returns none of the stored rows.
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Oracle, the world's most popular DBMS, is powerful and robust, running on many different operating systems.
Answer: A
Correct answer: True
Oracle runs on Unix, Linux, Windows and mainframe platforms alike, and it has long led the market for enterprise relational database systems. The claim is a general one about the product’s reach rather than a technical point, and the portability is the part that matters to a developer: the same SQL and PL/SQL run on any of those platforms.
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To see the contents of the SQL*Plus buffer, type:
Answer: D
Correct answer: LIST.
LIST, or L, displays the contents of the SQL buffer with the lines numbered, so that a particular line can be selected and changed before the statement is re-run with a slash. It is part of the small line-editing facility SQL*Plus provides for correcting a statement without retyping it.
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