多选题Which two statements are true regarding single row functions?（）AThey accept only a single argumentBThey can be nested only to two levelsCArguments can only be column values or constantsDThey always return a single result row for every row of a queried 

Listeners use only the TCP/IP protocol.

Multiple listener processes can run simultaneously on a host.

Multiple database instances can be registered with a single listener.

The listener-related errors can be traced only at the administrative level.

Only one database instance can be registered with a single listener at any time

An interface can only belong to single Flex Links.

An interface can belong to multiple Flex Links.

Flex Links operate only over single pairs of links.

Flex Links automatically disable STP so no BPDUs are propagated.

The LIKE operator cannot be used with single-row subqueries 

The NOT IN operator is equivalent to IS NULL with single-row subqueries 

=ANY and =ALL operators have the same functionality in multiple-row subqueries 

The NOT operator can be used with IN, ANY, and ALL operators in multiple-row subqueries 

A single row subquery can retrieve data from only one table.

A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.

A SQL query statement can display data from table B that is referred to in its subquery, without including B in its own FROM clause.

A single row subquery can retrieve data from more than one table.

A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.

A multiple-row subquery cannot be used in an INSERT statement to insert multiple rows at a time.

cannot be nested

manipulate data items

act on each row returned

return one result per row

accept only one argument and return only one value

accept arguments which can be a column or an expression

Listeners use only the TCP/IP protocol.

Multiple listener processes can run simultaneously on a host.

Multiple database instances can be registered with a single listener.

The listener-related errors can be traced only at the administrative level.

Only one database instance can be registered with a single listener at any time.

A single row subquery can retrieve only one column and one row.

A single row subquery can retrieve only one row but many columns.

A multiple row subquery can retrieve multiple rows and multiple columns.

A multiple row subquery can be compared by using the “>” operator.

A single row subquery can use the IN operator.

A multiple row subquery can use the “=” operator.

You can use aggregate functions in any clause of a SELECT statement.

You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.

You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.

You can pass column names, expressions, constants, or functions as parameters to an aggregate function.

You can use aggregate functions on a table, only by grouping the whole table as one single group.

You cannot group the rows of a table by more than one column while using aggregate functions.

a server instance can be associated with multiple machines

a machine can be associated with multiple server instance

a server instance can be associated with only a single machine

a machine can be associated with only one server instance

The nested query executes after the outer query returns the row.

The nested query executes first and then the outer query executes.

The outer query executes only once for the result returned by the inner query.

Each row returned by the outer query is evaluated for the results returned by the inner query.

A subquery should retrieve only one row.

A subquery can retrieve zero or more rows.

A subquery can be used only in SQL query statements.

Subqueries CANNOT be nested by more than two levels.

A subquery CANNOT be used in an SQL query statement that uses group functions.

When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.

They can accept only one argument.

They can be nested up to only two levels.

They can return multiple values of more than one data type.

They can be used in SELECT， WHERE， and ORDER BY clauses.

They can modify the data type of the argument that is referenced.

They can accept a column name， expression， variable name， or a user-supplied constant as arguments.