Oracle 12c: SQL - Chapter 3

11 September 2022
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question
A table name must begin with a(n) *number*.
answer
False
question
When a column is deleted, the deletion is permanent.
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True
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An automatic column will generate a value at runtime and may reference values from other columns.
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False
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The INTERVAL datatype can be used to identify a specific interval, or amount, of time.
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True
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*DDL* commands are used to create or modify database objects.
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True
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The DELETE TABLE command can be used to remove a table from a database.
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False
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Every table name within a specific schema must be unique.
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True
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A table name can consist of numbers, letters, and blank spaces.
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False
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The *MODIFY* clause can be included in the ALTER TABLE command to add a default value to an existing column.
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True
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You cannot specify the width for a(n) *NUMBER* column.
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False
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The data contained in a dropped table can be retrieved if the *DROP* option was not used in the DROP TABLE command.
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False
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The ALPHANUMERIC datatype can be used to store characters and numbers to a maximum width of 2000.
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False
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Once a column as been set as *UNUSED*, it cannot be recovered.
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True
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The width of a NUMBER column cannot be *changed* once it contains data.
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False
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The *scale* of a NUMBER column indicates the total number of digits that can be stored in the column.
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False
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The default size of the CHAR column is *2*.
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False
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SELECT9 *is* a valid table name.
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True
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You cannot delete the last column in a table.
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True
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The CREATE TABLE cannot contain a subquery.
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False
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More than one column can be changed at a time with the *ALTER TABLE...MODIFY* command.
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True
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Only one column can be added to an existing table at one time.
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False
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The syntax of the *CREATE TABLE* command requires that the column list be enclosed in parentheses.
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True
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A database must be shut down before the ALTER TABLE command can be executed.
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False
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A column name can consist of up to 225 characters.
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False
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The DELETE TABLE command can be used to delete all the data stored in a table and release the storage space, yet retain the structure of the table.
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False
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Which of the following keywords is used to mark a column for deletion at a later time?
answer
‚ÄčALTER TABLE...SET UNUSED
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Which of the following commands will add a new column named FIRST ORDER DATE to the CUSTOMERS table to store the date that the customer first placed an order with the company?
answer
‚ÄčALTER TABLE customers ADD (firstorderdate DATE);
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Which keywords are used to complete the deletion of a column previously marked with SET UNUSED?
answer
‚ÄčDROP UNUSED COLUMNS
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Which of the following is a valid column name?
answer
‚ÄčNEW_COLUMN
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Which of the following commands can be used to make structural changes to an existing table?
answer
‚ÄčALTER TABLE
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Which of the following keywords uses a subquery to create a new table using existing database tables?
answer
‚ÄčCREATE TABLE...AS
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A _______ column generates values automatically at runtime and may reference values from other columns.
answer
‚ÄčVirtual
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If a new column is added to the PROMOTION table, where will the new column be listed?
answer
‚Äčafter the MAXRETAIL column
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Which command instructs Oracle 12c to create a new table?
answer
‚ÄčCREATE TABLE
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Which of the following is displayed by the DESCRIBE command?
answer
‚Äčall of the above
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The maximum width of the NUMBER datatype is ____ digits.
answer
‚Äč38
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In which format does Oracle 12c display a date value?
answer
‚ÄčDD-MON-YY
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Which of the following datatypes refers to fixed-length character data, where n represents the maximum length of the column?
answer
‚ÄčCHAR(n)
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If a new table is being created based upon a subquery, the subquery must be enclosed in which of the following symbols?
answer
‚Äč( )
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Which command is used to rename a table you own?
answer
‚ÄčRENAME...TO
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If the MAXRETAIL column of the PROMOTION table has been set as unused, which of the following commands is valid?
answer
‚ÄčALTER TABLE promotion DROP UNUSED COLUMNS;
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When creating a table, which of the following statements is correct?
answer
‚ÄčThe column list must be enclosed in parentheses ( ).
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Which of the following commands will set the MINRETAIL column of the PROMOTION table as unused?
answer
‚Äčboth a and c
question
When using the ALTER TABLE...DROP COLUMN command, which of the following is not correct?
answer
‚ÄčThe command can be used to delete multiple columns from a table.
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Which of the following commands will change the name of the LAST NAME column to LAST_NAME in the CUSTOMERS table?
answer
‚Äčnone of the above
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Which of the following symbols cannot be used in a table name?
answer
‚Äč%
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A(n) ____ simply identifies the type of data that Oracle 12c will be expected to store in a column.
answer
‚Äčdatatype
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Which command instructs Oracle 12c to create a new table from existing data?
answer
‚ÄčCREATE TABLE...AS
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Which of the following queries will allow hidden columns to be displayed?
answer
‚ÄčSELECT which specifically references the hidden column.
question
Which of the following datatypes refers to variable-length character data, where n represents the maximum length of the column?
answer
‚ÄčVARCHAR2(n)