Oracle9i SQL Reference Release 2 (9.2) Part Number A9654002 


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SQL functions are built into Oracle and are available for use in various appropriate SQL statements. Do not confuse SQL functions with user functions written in PL/SQL.
If you call a SQL function with an argument of a datatype other than the datatype expected by the SQL function, then Oracle implicitly converts the argument to the expected datatype before performing the SQL function. If you call a SQL function with a null argument, then the SQL function automatically returns null. The only SQL functions that do not necessarily follow this behavior are CONCAT
, NVL
, and REPLACE
.
In the syntax diagrams for SQL functions, arguments are indicated by their datatypes. When the parameter "function" appears in SQL syntax, replace it with one of the functions described in this section. Functions are grouped by the datatypes of their arguments and their return values.
See Also:

The syntax showing the categories of functions follows:
function::=
single_row_function::=
The sections that follow list the builtin SQL functions in each of the groups illustrated in the preceding diagrams except userdefined functions. All of the builtin SQL functions are then described in alphabetical order. Userdefined functions are described at the end of this chapter.
Singlerow functions return a single result row for every row of a queried table or view. These functions can appear in select lists, WHERE
clauses, START
WITH
and CONNECT
BY
clauses, and HAVING
clauses.
Number functions accept numeric input and return numeric values. Most of these functions return values that are accurate to 38 decimal digits. The transcendental functions COS
, COSH
, EXP
, LN
, LOG
, SIN
, SINH
, SQRT
, TAN
, and TANH
are accurate to 36 decimal digits. The transcendental functions ACOS
, ASIN
, ATAN
, and ATAN2
are accurate to 30 decimal digits. The number functions are:
ABS
ACOS
ASIN
ATAN
ATAN2
BITAND
CEIL
COS
COSH
EXP
FLOOR
LN
LOG
MOD
POWER
ROUND (number)
SIGN
SIN
SINH
SQRT
TAN
TANH
TRUNC (number)
WIDTH_BUCKET
Character functions that return character values return values of the same datatype as the input argument.
CHAR
values are limited in length to 2000 bytes.VARCHAR2
values are limited in length to 4000 bytes.
For both of these types of functions, if the length of the return value exceeds the limit, then Oracle truncates it and returns the result without an error message.
CLOB
values are limited to 4 GB.
For CLOB
functions, if the length of the return values exceeds the limit, then Oracle raises an error and returns no data.
The character functions that return character values are:
CHR
CONCAT
INITCAP
LOWER
LPAD
LTRIM
NLS_INITCAP
NLS_LOWER
NLSSORT
NLS_UPPER
REPLACE
RPAD
RTRIM
SOUNDEX
SUBSTR
TRANSLATE
TREAT
TRIM
UPPER
Character functions that return number values can take as their argument any character datatype.
The character functions that return number values are:
Datetime functions operate on values of the DATE
datatype. All datetime functions return a datetime or interval value of DATE
datatype, except the MONTHS_BETWEEN
function, which returns a number. The datetime functions are:
ADD_MONTHS
CURRENT_DATE
CURRENT_TIMESTAMP
DBTIMEZONE
EXTRACT (datetime)
FROM_TZ
LAST_DAY
LOCALTIMESTAMP
MONTHS_BETWEEN
NEW_TIME
NEXT_DAY
NUMTODSINTERVAL
NUMTOYMINTERVAL
ROUND (date)
SESSIONTIMEZONE
SYS_EXTRACT_UTC
SYSDATE
SYSTIMESTAMP
TO_DSINTERVAL
TO_TIMESTAMP
TO_TIMESTAMP_TZ
TO_YMINTERVAL
TRUNC (date)
TZ_OFFSET
Conversion functions convert a value from one datatype to another. Generally, the form of the function names follows the convention datatype
TO
datatype
. The first datatype is the input datatype. The second datatype is the output datatype. The SQL conversion functions are:
ASCIISTR
BIN_TO_NUM
CAST
CHARTOROWID
COMPOSE
CONVERT
DECOMPOSE
HEXTORAW
NUMTODSINTERVAL
NUMTOYMINTERVAL
RAWTOHEX
RAWTONHEX
ROWIDTOCHAR
ROWIDTONCHAR
TO_CHAR (character)
TO_CHAR (datetime)
TO_CHAR (number)
TO_CLOB
TO_DATE
TO_DSINTERVAL
TO_LOB
TO_MULTI_BYTE
TO_NCHAR (character)
TO_NCHAR (datetime)
TO_NCHAR (number)
TO_NCLOB
TO_NUMBER
TO_SINGLE_BYTE
TO_YMINTERVAL
TRANSLATE ... USING
UNISTR
The following singlerow functions do not fall into any of the other singlerow function categories:
BFILENAME
COALESCE
DECODE
DEPTH
DUMP
EMPTY_BLOB, EMPTY_CLOB
EXISTSNODE
EXTRACT (XML)
EXTRACTVALUE
GREATEST
LEAST
NLS_CHARSET_DECL_LEN
NLS_CHARSET_ID
NLS_CHARSET_NAME
NULLIF
NVL
NVL2
PATH
SYS_CONNECT_BY_PATH
SYS_CONTEXT
SYS_DBURIGEN
SYS_EXTRACT_UTC
SYS_GUID
SYS_TYPEID
SYS_XMLAGG
SYS_XMLGEN
UID
UPDATEXML
USER
USERENV
VSIZE
XMLAGG
XMLCOLATTVAL
XMLCONCAT
XMLFOREST
XMLSEQUENCE
XMLTRANSFORM
Aggregate functions return a single result row based on groups of rows, rather than on single rows. Aggregate functions can appear in select lists and in ORDER
BY
and HAVING
clauses. They are commonly used with the GROUP
BY
clause in a SELECT
statement, where Oracle divides the rows of a queried table or view into groups. In a query containing a GROUP
BY
clause, the elements of the select list can be aggregate functions, GROUP
BY
expressions, constants, or expressions involving one of these. Oracle applies the aggregate functions to each group of rows and returns a single result row for each group.
If you omit the GROUP
BY
clause, then Oracle applies aggregate functions in the select list to all the rows in the queried table or view. You use aggregate functions in the HAVING
clause to eliminate groups from the output based on the results of the aggregate functions, rather than on the values of the individual rows of the queried table or view.
See Also:
"Using the GROUP BY Clause: Examples" and the "HAVING Clause" for more information on the 
Many (but not all) aggregate functions that take a single argument accept these clauses:
DISTINCT
causes an aggregate function to consider only distinct values of the argument expression.ALL
causes an aggregate function to consider all values, including all duplicates.For example, the DISTINCT
average of 1, 1, 1, and 3 is 2. The ALL
average is 1.5. If you specify neither, then the default is ALL
.
All aggregate functions except COUNT
(*) and GROUPING
ignore nulls. You can use the NVL
function in the argument to an aggregate function to substitute a value for a null. COUNT
never returns null, but returns either a number or zero. For all the remaining aggregate functions, if the data set contains no rows, or contains only rows with nulls as arguments to the aggregate function, then the function returns null.
You can nest aggregate functions. For example, the following example calculates the average of the maximum salaries of all the departments in the sample schema hr
:
SELECT AVG(MAX(salary)) FROM employees GROUP BY department_id; AVG(MAX(SALARY))  10925
This calculation evaluates the inner aggregate (MAX
(salary
)) for each group defined by the GROUP
BY
clause (department_id
), and aggregates the results again.
The aggregate functions are:
AVG
CORR
COUNT
COVAR_POP
COVAR_SAMP
CUME_DIST
DENSE_RANK
FIRST
GROUP_ID
GROUPING
GROUPING_ID
LAST
MAX
MIN
PERCENTILE_CONT
PERCENTILE_DISC
PERCENT_RANK
RANK
REGR_ (Linear Regression) Functions
STDDEV
STDDEV_POP
STDDEV_SAMP
SUM
VAR_POP
VAR_SAMP
VARIANCE
Analytic functions compute an aggregate value based on a group of rows. They differ from aggregate functions in that they return multiple rows for each group. The group of rows is called a window and is defined by the analytic clause. For each row, a "sliding" window of rows is defined. The window determines the range of rows used to perform the calculations for the "current row". Window sizes can be based on either a physical number of rows or a logical interval such as time.
Analytic functions are the last set of operations performed in a query except for the final ORDER
BY
clause. All joins and all WHERE
, GROUP
BY
, and HAVING
clauses are completed before the analytic functions are processed. Therefore, analytic functions can appear only in the select list or ORDER
BY
clause.
Analytic functions are commonly used to compute cumulative, moving, centered, and reporting aggregates.
analytic_function::=
analytic_clause::=
The semantics of this syntax are discussed in the sections that follow.
Specify the name of an analytic function (see the listing of analytic functions following this discussion of semantics).
Analytic functions take 0 to 3 arguments.
Use OVER
analytic_clause
to indicate that the function operates on a query result set. That is, it is computed after the FROM
, WHERE
, GROUP
BY
, and HAVING
clauses. You can specify analytic functions with this clause in the select list or ORDER
BY
clause. To filter the results of a query based on an analytic function, nest these functions within the parent query, and then filter the results of the nested subquery.
Notes:

Use the PARTITION
BY
clause to partition the query result set into groups based on one or more value_expr
. If you omit this clause, then the function treats all rows of the query result set as a single group.
You can specify multiple analytic functions in the same query, each with the same or different PARTITION
BY
keys.
Note: If the objects being queried have the parallel attribute, and if you specify an analytic function with the 
Valid values of value_expr
are constants, columns, nonanalytic functions, function expressions, or expressions involving any of these.
Use the order_by_clause
to specify how data is ordered within a partition. For all analytic functions except PERCENTILE_CONT
and PERCENTILE_DISC
(which take only a single key), you can order the values in a partition on multiple keys, each defined by a value_expr
and each qualified by an ordering sequence.
Within each function, you can specify multiple ordering expressions. Doing so is especially useful when using functions that rank values, because the second expression can resolve ties between identical values for the first expression.
Note: Whenever the 
When used in an analytic function, the order_by_clause
must take an expression (expr
). The SIBLINGS
keyword is not valid (it is relevant only in hierarchical queries). Position (position
) and column aliases (c_alias
) are invalid. Otherwise this order_by_clause
is the same as that used to order the overall query or subquery.
Specify the ordering sequence (ascending or descending). ASC
is the default.
Specify whether returned rows containing nulls should appear first or last in the ordering sequence.
NULLS
LAST
is the default for ascending order, and NULLS
FIRST
is the default for descending order.
See Also:

Some analytic functions allow the windowing_clause
. In the listing of analytic functions at the end of this section, the functions that allow the windowing_clause
are followed by an asterisk (*).
These keywords define for each row a "window" (a physical or logical set of rows) used for calculating the function result. The function is then applied to all the rows in the window. The window "slides" through the query result set or partition from top to bottom.
You cannot specify this clause unless you have specified the order_by_clause
.
Use the BETWEEN
... AND
clause to specify a start point and end point for the window. The first expression (before AND
) defines the start point and the second expression (after AND
) defines the end point.
If you omit BETWEEN
and specify only one end point, then Oracle considers it the start point, and the end point defaults to the current row.
Specify UNBOUNDED
PRECEDING
to indicate that the window starts at the first row of the partition. This is the start point specification and cannot be used as an end point specification.
Specify UNBOUNDED
FOLLOWING
to indicate that the window ends at the last row of the partition. This is the end point specification and cannot be used as a start point specification.
As a start point, CURRENT
ROW
specifies that the window begins at the current row or value (depending on whether you have specified ROW
or RANGE
, respectively). In this case the end point cannot be value_expr
PRECEDING
.
As an end point, CURRENT
ROW
specifies that the window ends at the current row or value (depending on whether you have specified ROW
or RANGE
, respectively). In this case the start point cannot be value_expr
FOLLOWING
.
For RANGE
or ROW
:
value_expr
FOLLOWING
is the start point, then the end point must be value_expr
FOLLOWING
.value_expr
PRECEDING
is the end point, then the start point must be value_expr
PRECEDING
.If you are defining a logical window defined by an interval of time in numeric format, then you may need to use conversion functions.
See Also:
NUMTOYMINTERVAL and NUMTODSINTERVAL for information on converting numeric times into intervals 
If you specified ROWS
:
value_expr
is a physical offset. It must be a constant or expression and must evaluate to a positive numeric value.value_expr
is part of the start point, then it must evaluate to a row before the end point.If you specified RANGE
:
value_expr
is a logical offset. It must be a constant or expression that evaluates to a positive numeric value or an interval literal.
See Also:
"Literals" for information on interval literals 
order_by_clause
value_expr
evaluates to a numeric value, then the ORDER
BY
expr
must be a NUMBER
or DATE
datatype.value_expr
evaluates to an interval value, then the ORDER
BY
expr
must be a DATE
datatype.If you omit the windowing_clause
entirely, then the default is RANGE
BETWEEN
UNBOUNDED
PRECEDING
AND
CURRENT
ROW
.
Analytic functions are commonly used in data warehousing environments. The analytic functions follow. Functions followed by an asterisk (*) allow the full syntax, including the windowing_clause
.
AVG *
CORR *
COVAR_POP *
COVAR_SAMP *
COUNT *
CUME_DIST
DENSE_RANK
FIRST
FIRST_VALUE *
LAG
LAST
LAST_VALUE *
LEAD
MAX *
MIN *
NTILE
PERCENT_RANK
PERCENTILE_CONT
PERCENTILE_DISC
RANK
RATIO_TO_REPORT
REGR_ (Linear Regression) Functions *
ROW_NUMBER
STDDEV *
STDDEV_POP *
STDDEV_SAMP *
SUM *
VAR_POP *
VAR_SAMP *
VARIANCE *
See Also:
Oracle9i Data Warehousing Guide for more information on these functions, and for scenarios illustrating their use 
Object reference functions manipulate REFs, which are references to objects of specified object types. The object reference functions are:
DEREF
MAKE_REF
REF
REFTOHEX
VALUE
See Also:
Oracle9i Database Concepts and Oracle9i Application Developer's Guide  Fundamentals for more information about REFs 
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