NUMTODSINTERVAL

SELECT e.last_name, NULLIF(e.job_id, j.job_id) "Old Job ID"

FROM employees e, job_history j

WHERE e.employee_id = j.employee_id

ORDER BY last_name;

NUMTODSINTERVAL

Syntax numtodsinterval::=

NUMTODSINTERVAL ( n , ’ char_expr ’ )

Purpose

NUMTODSINTERVAL converts n to an INTERVAL DAY TO SECOND literal. n can be a number or an expression resolving to a number. char_expr can be of CHAR, VARCHAR2, NCHAR, or NVARCHAR2 datatype. The value for char_expr specifies the unit of n and must resolve to one of the following string values:

char_expr is case insensitive. Leading and trailing values within the parentheses are ignored. By default, precision of the return is 9.

Functions 6-111

NUMTOYMINTERVAL

Examples

The following example calculates, for each employee, the number of employees hired by the same manager within the last 100 days from his/her hire date:

SELECT manager_id, last_name, hire_date,

COUNT(*) OVER (PARTITION BY manager_id ORDER BY hire_date

RANGE NUMTODSINTERVAL(100, ’day’) PRECEDING) AS t_count

FROM employees;

NUMTOYMINTERVAL

Syntax numtoyminterval::=

NUMTOYMINTERVAL ( n , ’ char_expr ’ )

Purpose

NUMTOYMINTERVAL converts number n to an INTERVAL YEAR TO MONTH literal. n can be a number or an expression resolving to a number. char_expr can be of

CHAR, VARCHAR2, NCHAR, or NVARCHAR2 datatype. The value for char_expr specifies the unit of n, and must resolve to one of the following string values:

char_expr is case insensitive. Leading and trailing values within the parentheses are ignored. By default, precision of the return is 9.

6-112 Oracle9i SQL Reference

NVL

Examples

The following example calculates, for each employee, the total salary of employees hired in the past one year from his/her hire date.

SELECT last_name, hire_date, salary, SUM(salary)

OVER (ORDER BY hire_date

RANGE NUMTOYMINTERVAL(1,’year’) PRECEDING) AS t_sal

FROM employees;

NVL

Syntax nvl::=

NVL ( expr1 , expr2 )

Purpose

NVL lets you replace a null (blank) with a string in the results of a query. If expr1 is null, then NVL returns expr2. If expr1 is not null, then NVL returns expr1. The arguments expr1 and expr2 can have any datatype. If their datatypes are different, then Oracle converts expr2 to the datatype of expr1 before comparing them.

The datatype of the return value is always the same as the datatype of expr1, unless expr1 is character data, in which case the return value’s datatype is VARCHAR2 and is in the character set of expr1.

Functions 6-113

NVL2

Examples

The following example returns a list of employee names and commissions, substituting "Not Applicable" if the employee receives no commission:

SELECT last_name, NVL(TO_CHAR(commission_pct), ’Not Applicable’) "COMMISSION" FROM employees

WHERE last_name LIKE ’B%’ ORDER BY last_name;

NVL2

Syntax nvl2::=

NVL2 ( expr1 , expr2 , expr3 )

Purpose

NVL2 lets you determine the value returned by a query based on whether a specified expression is null or not null. If expr1 is not null, then NVL2 returns expr2. If expr1 is null, then NVL2 returns expr3. The argument expr1 can have any datatype. The arguments expr2 and expr3 can have any datatypes except

LONG.

If the datatypes of expr2 and expr3 are different, then Oracle converts expr3 to the datatype of expr2 before comparing them unless expr3 is a null constant. In that case, a datatype conversion is not necessary.

The datatype of the return value is always the same as the datatype of expr2, unless expr2 is character data, in which case the return value’s datatype is

VARCHAR2.

6-114 Oracle9i SQL Reference