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Self assessment questions from the lecturer on my.unisa

A database language enables the user to create database and table structures to perform basic data management chores.

True

A database language enables the user to perform complex queries designed to transform the raw data into useful information.

True

The ANSI prescribes a standard SQL-the current fully approved version is known as SQL-07.

False

The ANSI SQL standards are also accepted by the ISO.

True

SQL is considered difficult to learn; its command set has a vocabulary of more than 300 words.

False

Data type selection is usually dictated by the nature of the data and by the intended use.

True

Only numeric data types can be added and subtracted in SQL.

False

Entity integrity is enforced automatically when the primary key is specified in the CREATE TABLE command sequence.

True

The CHECK constraint is used to define a condition for the values that the attribute domain cannot have.

False

SQL requires the use of the ADD command to enter data into a table.

False

You cannot insert a row containing a null attribute value using SQL.

False

To list the contents of a table, you must use the DISPLAY command.

False

Any changes made to the contents of a table are not physically saved on disk until you use the SAVE <table name> command.

False

The COMMIT command does not permanently save all changes. In order to do that, you must use SAVE.

False

If you have not yet used the COMMIT command to store the changes permanently in the database, you can restore the database to its previous condition with the ROLLBACK command.

True

All SQL commands must be issued on a single line.

False

Although SQL commands can be grouped together on a single line, complex command sequences are best shown on separate lines, with space between the SQL command and the command's components.

True

You can select partial table contents by naming the desired fields and by placing restrictions on the rows to be included in the output.

True

Oracle users can use the Access QBE (query by example) query generator.

False

Since computers identify all characters by their numeric codes, mathematical operators cannot be used to place restrictions on character-based attributes.

False

String comparisons are made from left to right.

True

Date procedures are often more software-specific than other SQL procedures.

True

SQL allows the use of logical restrictions on its inquiries such as OR, AND, and NOT.

True

ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause.

True

The conditional LIKE must be used in conjunction with wildcard characters.

True

Most SQL implementations yield case-insensitive searches.

False

Some RDBMSs, such as Microsoft Access, automatically make the necessary conversions to eliminate case sensitivity.

True

The COUNT function is designed to tally the number of non-null "values" of an attribute, and is often used in conjunction with the DISTINCT clause.

True

To join tables, simply enumerate the tables in the FROM clause of the SELECT statement. The DBMS will create a Cartesian product of every table in the FROM clause. To get the correct results, you need to select the rows in which the common attribute values do not match.

False

When joining three or more tables, you need to specify a join condition for one pair of tables.

False

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