PL-SQL Functions
Comparison Operators
Select Operators
Single Row Functions for Numbers, Chars and Dates
Conversion Functions
Miscellaneous Single Row Functions
Aggregate Functions
Analytical Functions
Object Reference Functions
Date Format Models
Date Prefixes and Suffixes
Number Format Models
NULL Related Functions


Comparison Operators

Table 1-1. Comparison Operators

Operator

What it does

= true if two expressions are equal
!= ^= -= <> logically equivalent—true if two expressions are not equal
> True if left expression is greater than right expression
>= True if left expression is greater than or equal to right expression
< True if left expression is less than right expression
<= True if left expression is less than or equal to right expression
IN Is equal to any member of a set or subquery
NOT IN Does NOT equal any member of a set or subquery
ANY, SOME True if one or more of the values in the list of expressions or subquery satisfies the condition
ALL True if all of the values in the list of expressions or subquery satisfies the condition
BETWEEN x AND y True if greater than or equal to x and less than or equal to y (can be reversed in meaning with NOT)
EXISTS True if the subquery returns at least one row (can be reversed in meaning with NOT)
LIKE pattern [ESCAPE 'c'] 'True if expression or subquery matches pattern. '%' matches any sequence of characters, '_' matches any single character. If ESCAPE is used, the character 'c' causes the character following to be taken literally (can be reversed in meaning with NOT).
IS NULL TRUE if the value is NULL (can be reversed in meaning with NOT)


Select Operators

Also called SET operators

Table 1-2. Select Operators (Sets)

Operator

What it does

UNION This combines the results of two queries and returns the set of distinct rows returned by either query
UNION ALL This combines the results of two queries and returns all rows returned by either query, including duplicates
INTERSECT This combines the results of two queries and returns the set of distinct rows returned by both queries
MINUS This combines the results of two queries and returns the distinct rows that were in the first query, but not in the second

Table 1-3. Other Select Operators

Operator

What it does

(+) Denotes that the preceding column is an outer join
* Wildcard operator. Equals all columns in a select statement
PRIOR Denotes a parent-child relationship in a tree-structured query
ALL Include all duplicate rows in a query (the default)
DISTINCT Eliminate duplicates in a result set


Single Row Functions

Number Functions

Table 1-6. Single Row Number Functions

Function

What it does

ABS(n) Returns absolute value of n
ACOS(n) Returns arc cosine of n in radians
ASIN(n) Returns arc sine of n in radians
ATAN(n) Returns arc tangent of n, in radians
ATAN2(n,m) Returns the arc tangent of n and m, in radians
BITAND(n,m) Computes the bitwise logical AND of the bits of n and m, where n and m are nonnegative integers. Returns an integer.
CEIL(n) Ceiling function—returns the smallest integer >= n
COS(n) Returns the cosine of n where n is in radians
COSH(n) Returns the hyperbolic cosine of n where n is in radians
EXP(n) Returns en
FLOOR(n) Returns the largest integer <= n
LN(n) Returns the natural log of n
LOG(m,n) Returns the base m log of n
MOD(m,n) Returns the modulus of m, n—the remainder of m divided by n. (Returns m when n=0)
POWER(m,n) Returns m raised to the nth power
ROUND (m[,n]) Rounds m to the nearest n places. Where n is omitted, default is zero. n must be an integer
SIGN(n) For n < 0, returns –1, for n > 0, returns 1, for n = 0, returns 0
SIN(n) Returns sine(n) where n is in radians
SINH(n) Returns the hyperbolic sine(n) where n is in radians
SQRT(n) Returns the square root of n
TAN(n) Returns the tangent(n) where n is in radians
TANH(n) Returns the hyperbolic tangent(n) where n is in radians
TRUNC (m[,n]) Truncate. Returns m truncated to n places. Where n is omitted, it returns the integer value of m.
WIDTH_BUCKET (exp,min,max,num) Returns the “bucket” in which exp belongs, where min is the minimum value, max is the maximum value, and num is the number of divisions (buckets) to use

Character Functions

Table 1-7. Character Single Row Functions

Function

What it does

CHR (n) Returns the character whose binary value is n. Accepts USING NCHAR_CS clause
CONCAT (char1,char2) Combines two strings, char1 and char2
INITCAP(char) Returns char with the first character of each word in char capitalized
LOWER(char) Returns char with all characters converted to lowercase
LPAD(char1,n[,char2]) Returns char1 padded on the left to width n with character sequence in char2. Default padding is a single blank (space).
LTRIM(char[,set]) Returns char with initial characters in set removed from the left. Default set is a blank character (space).
NLS_INITCAP(char[,nlsparam]) Returns char with the first character of each word in char capitalized. Accepts an NLS parameter.
NLS_LOWER(char[,nlsparam]) Returns char with all characters converted to lowercase. Accepts an NLS parameter.
NLSSORT(char[,nlsparam]) Returns language specific sort of char. Accepts an NLS parameter.
NLS_UPPER(char[,nlsparam]) Returns char with all characters converted to uppercase. Accepts an NLS parameter.
REPLACE(char[,searchstring[,replacestring]]) Returns char with searchstring replaced by replacestring. Where replacestring is omitted or null, all instances of searchstring are removed. Where searchstring is omitted or null, char is returned.
RPAD(char1,n[,char2]) Returns char1 padded on the right to width n with character sequence in char2. Default padding is a single blank (space).
RTRIM(char[,set]) Returns char with initial characters in set removed from the right. Default set is a blank character (space).
SOUNDEX(char) Returns the phonetic equivalent of char. Allows for searches for words that sound alike but are spelled differently.
SUBSTR(string,n[,m])

Returns the substring of string, starting at position n, for a length of m (or to the end of string if m is not present). Example:
Substring End of String
SELECT SUBSTR('Take the first four characters', 16) SIXTEEN_TO_END FROM dual;
SIXTEEN_TO_END
---------------
four characters
TRANSLATE(char,from,to) Returns char, with all occurrences of characters in the from string replaced with the corresponding character in the to string. If to is shorter than from, then from characters without a corresponding to character will be removed. Empty to returns NULL, not an empty string.
TREAT(exp AS [[REF] [schema.]] type) Changes the declared type of exp to type
TRIM([[LEADING|TRAILING|BOTH] [trimchar]FROM]source) Returns source with leading and/or trailing trimchars removed. Default trimchar is a blank space, default action is to remove both leading and trailing blank spaces.
UPPER (char) Returns char with all characters converted to uppercase
ASCII (char) Returns the number value of the first character of char
INSTR(str,substr[,pos[,occur]])
“In string” function. Returns the position of the occurrence occur of substr in str, starting at pos. Default for pos and occur is 1. If pos is negative, search works backwards from the end of str.
LENGTH (char)  Returns the length of char

Date Functions

Table 1-8. Date Single Row Functions

Function

What it does

ADD_MONTHS(d,n) Returns the date d plus n months. If d is the last day of the month, or d+n would be past the end of the month, returns the last day of the month.
CURRENT_DATE Returns the current Gregorian date as datatype DATE, in the session specific time zone
CURRENT_TIMESTAMP [(precision)] Returns the current date and time as datatype TIMESTAMP WITH TIME ZONE, in the session specific time zone. Precision defaults to 6 places.
DBTIMEZONE Returns the time zone of the database
EXTRACT (datetime FROM expr) datetime can be YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, TIMEZONE_HOUR, TIMEZONE_MINUTE, TIMEZONE_REGION, or TIMEZONE_ABBR, and expr can be either an internal value or datetime value expression
FROM_TZ(timestamp, time_zone) Returns timestamp converted to a TIMESTAMP WITH TIME ZONE value, using time_zone
LAST_DAY(date) Returns the date of the last day of the month containing date
LOCALTIMESTAMP [(precision)] Returns the current date and time of the session in datatype TIMESTAMP of precision
MONTHS_BETWEEN(date1, date2) Returns the number of months between date1 and date2
NEW_TIME(date,zone1,zone2) Returns date converted from time zone zone1 to zone2. NLS_DATE_FORMAT must be set to a 24-hour format.
NEXT_DAY(date,weekday) Returns the next weekday later than date where weekday is the day of the week or its abbreviation
NUMTODSINTERVAL (n, char) Returns n converted to an INTERVAL DAY TO SECOND literal. char can be 'DAY,' 'HOUR,' 'MINUTE,' or 'SECOND,' or an expression that resolves to one of those
NUMTOYMINTERVAL (n, char) Returns n converted to an INTERVAL YEAR TO MONTH literal. char can be 'MONTH' or 'YEAR' or an expression that resolves to one of those
ROUND (date[,fmt]) Returns date rounded to the nearest unit specified by the format model fmt. Defaults to the nearest day.
SESSIONTIMEZONE Returns the time zone of the current session, either as a time zone offset or a time zone region name, depending on the format used for the most recent ALTER SESSION statement
SYS_EXTRACT_UTC (datetz) Extracts the UTC value of datetz where datetz is a datetime with time zone displacement
SYSDATE Returns the current date and time
SYSTIMESTAMP Returns the system timestamp in TIMESTAMP WITH TIME ZONE datatype
TO_DSINTERVAL(char [nlsparm]) Converts char to an INTERVAL DAY TO SECOND type
TO_TIMESTAMP (char[,fmt[nlsparm]]) Converts char to datatype of TIMESTAMP. fmt specifies the format of char if other than the default for datatype TIMESTAMP
TO_TIMESTAMP_TZ (char[,fmt[nlsparm]]) Converts char to datatype of TIMESTAMP WITH TIME ZONE. fmt specifies the format of char if other than the default for datatype TIMESTAMP WITH TIME ZONE.
TO_YMINTERVA(char) Converts char to an INTERVAL YEAR TO MONTH type
TRUNC (date[,fmt]) Returns date truncated to the time unit specified by fmt. If fmt is omitted, date is truncated to the nearest day.
TZ_OFFSET(tzname | SESSIONTIMEZONE | DBTIMEZONE | '+|-hh:mi') Returns the timezone offset

Conversion Functions

Table 1-9. Conversion Single Row Functions

Function

What it does

ASCIISTR(string) Returns the ASCII string in the database language of string which can be in any character set. Non-ASCII characters are converted to their UTF-16 binary values.
BIN_TO_NUM(expr[,expr…]) Converts the binary bits of expr,expr,… to a number. Example: BIN_TO_NUM(1,1,0,1) returns 13.
CAST(expr | [MULTISET] (subquery) AS type) Converts from one built in datatype or collection type to another
CHARTOROWID(char) Converts char to type ROWID
COMPOSE('string') Converts string to its Unicode string equivalent in the same character set
CONVERT(char, dest_set [,source_set]) Returns char converted from source_set character set to dest_set character set. If source_set is not specified, the database character set is assumed.
DECOMPOSE(string [CANONICAL | COMPATIBILITY]) Returns a unicode string decomposed from its fully normalized form. If CANONICAL(the default) is used, the result can be recomposed with COMPOSE.
HEXTORAW (char) Returns hexadecimal digits of char as RAW
NUMTODSINTERVAL (n, char) Converts number n to an INTERVAL DAY TO SECOND literal. char can be 'DAY,' 'HOUR,' 'MINUTE,' or 'SECOND'
NUMTOYMINTERVAL (n, char) Converts number n to an INTERVAL YEAR TO MONTH literal. char can be 'YEAR or 'MONTH'
RAWTOHEX(raw) Converts raw to its hexadecimal equivalent character value
RAWTONHEX(raw) Converts raw to its hexadecimal equivalent NVARCHAR2 character value
ROWIDTOCHAR(rowid) Converts rowid to a VARCHAR2 18 characters long
ROWIDTONCHAR(rowid) Converts rowid to a NVARCHAR2 18 characters long
TO_CHAR (nchar | clob | nclob) Converts an NCHAR, NVARCHAR2, CLOB or NCLOB value to the underlying database character set
TO_CHAR (date [,fmt[nlsparm]]) Converts date to VARCHAR2, using format fmt and any nlsparm
TO_CHAR (num [,fmt[nlsparm]]) Converts num to VARCHAR2, using format fmt and any nlsparm
TO_CLOB (lob_col|char) Converts lob_col or char to CLOB value
TO_DATE char [,fmt[nlsparm]] Converts char to a date, using the format fmt and any nlsparm. If fmt is not specified, then the default date format is used.
TO_DSINTERVAL (char [nlsparm]) Converts char to an INTERVAL DAY TO SECOND literal
TO_LOB(long_col) Converts the LONG or LONG RAW value of long_col to LOB values
TO_MULTI_BYTE(char) Converts single byte char to multibyte characters
TO_NCHAR(char [,fmt[nlsparm]]) Converts a string from the database character set to the national character set
TO_NCHAR (datetime | interval[,fmt[nlsparm]]) Converts a date, time, or interval value from the database character set to the national character set
TO_NCHAR (n [,fmt[nlsparm]]) Converts a number to a string in the NVARCHAR2 character set
TO_NCLOB (lob_column | char) Converts char or lob_column to NCLOB data, using the national character set
TO_NUMBER(char[,fmt[nlsparm]]) Converts char to a number, using fmt as the format specifier
TO_SINGLE_BYTE(char) Returns char with any multibyte characters converted to the corresponding single byte characters
TO_YMINTERVAL(char [nlsparm]) Converts char to an INTERVAL YEAR TO MONTH literal
TRANSLATE (text USING CHAR_CS | NCHAR_CS) Returns text translated into the database character set (USING CHAR_CS) or the national character set (USING NCHAR_CS)
UNISTR(string) Returns string in Unicode using the database Unicode character set

Miscellaneous Single Row Functions

Table 1-10. Miscellaneous Single Row Functions

Function

What it does

BFILENAME('dir','fname') Returns a locator for an LOB binary file on the filesystem. dir is the database object that is an alias for the full pathname of the file directory, fname is the actual file name.
COALESCE(expr[,expr,...]) Returns the first nonnull expression in a list of expressions
DECODE(expr,search ,result [ ,search,result...][,default]) Searches expr for search, returning the specific result for each search. Returns default if search is not found.
DEPTH(correlation_int) Returns the number of levels in the path specified by an UNDER_PATH condition
DUMP(expr[,return_fmt [,start[,length]]]) Returns a VARCHAR2 value with the datatype, length, and internal representation of expr, using the format of return_fmt. Returns entire internal representation unless start and optionally length are specified.
EMPTY_BLOB() Returns a locator for a BLOB, allowing you to initialize the BLOB
EMPTY_CLOB() Returns a locator for a CLOB, allowing you to initialize the CLOB
EXISTSNODE(XML_Instance, path [expr]) Walks the XML tree and returns success if a node is found that matches the specified path
EXTRACT (XML_Instance, path [expr]) Walks the XML tree and, if nodes are found which match the specified path, returns those nodes
EXTRACTVALUE(XML_Instance, path [expr]) Walks the XML tree and, if nodes are found that match the specified path, returns the scalar value of those nodes
GREATEST(expr[,expr,...]) Returns the expression in the list with greatest value. All data types are implicitly converted to the data type of the first expression. Character comparisons use the database character set.
LEAST(expr[,expr,...]) Returns the expression in the list with least value. All data types are implicitly converted to the data type of the first expression. Character comparisons use the database character set.
NLS_CHARSET_DECL_LEN (bytes,set_id) Returns the declaration width of the NCHAR column of width bytes and a character set ID of set_id
NLS_CHARSET_ID(text) Returns the number of a character set ID with a character set name of text
NLS_CHARSET_NAME(num) Returns the character set name of the character set with ID num
NULLIF(expr1,expr2) Returns null if expr1and expr2 are equal, else returns expr1
NVL(expr1,expr2) Returns expr2 if expr1 is NULL, else returns expr1
NVL2(expr1,expr2,expr3) Returns expr2 if expr1 is NOT NULL, else returns expr3
PATH (correlation_int) Returns the relative path to the resource specified in an UNDER_PATH or EQUALS_PATH condition
SYS_CONNECT_BY_PATH (column,char) Returns the path of a column value from root to node in an hierarchical query. Column values are separated by char.
SYS_CONTEXT('namespace', 'param'[,len]) Returns a VARCHAR2 with the value of param of namespace. Return is 256 bytes unless overridden by len.
SYS_DBURIGEN(col|attr [rowid][,col|attr [rowid],...] [,'text()']) Generates a URL that can be used to retrieve an XML document from one or more columns col or attributes attr with or without a rowid
SYS_EXTRACT_UTC(time) Returns the UTC from time where time is a datetime with time zone displacement
SYS_GUID() Generates and then returns a Globally Unique IDentifier (GUID) of 16 RAW bytes
SYS_TYPEID(obj_val) Returns the typeid of an object type operand
SYS_XMLAGG(expr [fmt]) Creates a single well-formed XML document from multiple documents
SYS_XMLGEN(expr [fmt]) Creates a well-formed XML document from a database row/column expression
UID Returns the UID of the current session user
UPDATEXML(XML_instance, path, expr) Updates an XML document by searching for the node specified in the path, then replaces either the node or the scalar value of the node, depending on argument types
USER Returns the username of the current session user
USERENV(param) Returns a variety of information about the current session. While deprecated in favor of SYS_CONTEXT, this is retained for backward compatibility.
VSIZE(expr) Returns the number of bytes used by the value represented by expr
XMLAGG(XML_instance [ORDER BY sortlist]) Returns a well-formed XML document by aggregating a series of XML fragments. The returned document is a simple aggregate and no formatting is supported.
XMLCOLATTVAL Creates an XML fragment for one or more columns of a single row. The format of the fragment is fixed as <column name=”column name”>column value</column>.
XMLCONCAT(XML_instance [, XML_instance,...]) Returns an XML fragment created by concatenating a series of XML fragments or elements
XMLFOREST Creates an XML fragment for one or more columns of a single row. The format of the fragment is fixed as <column name>column value</column name>.
XMLSEQUENCE Used to “unroll” a stored XMLType into multiple rows for further processing as individual elements
XMLTRANSFORM Applies an XSL style sheet to an XML document and returns the resulting new XML document

Aggregate Functions

All of the aggregate functions described below can have an analytical clause appended to them using the OVER (analytical_clause) syntax. For space considerations, we've omitted this from the Function column.

Table 1-11. Aggregate Functions

Function

What it does

AVG([DISTINCT|ALL] expr) Computes the average of the rows returned by expr. If the DISTINCT keyword is used, duplicate rows will be excluded from the calculation.
CORR( expr1 , expr2 ) Calculates the coefficient of correlation between expr1 and expr2
COUNT(* | [DISTINCT|ALL] expr) Returns the number of [DISTINCT] rows in the expr that are not null, or if * is specified, the total number of rows, including duplicates and nulls
COVAR_POP( expr1, expr2 ) Given a set of pairs, expr1 and expr2, where nulls are excluded, returns the population covariance
COVAR_SAMP( expr1, expr2 ) Given a set of pairs, expr1 and expr2, where nulls are excluded, returns the sample covariance
CUME_DIST(expr[,expr...]) WITHIN GROUP (ORDER BY expr [DESC|ASC] [NULLS [FIRST|LAST]) Given a list of values, finds and returns the cumulative distribution of a single value within that list
DENSE_RANK(expr[,expr...]) WITHIN GROUP (ORDER BY expr) Given an ordered group of rows, finds and returns the rank of a single value within that group
FIRST ORDER BY expr [DESC|ASC] [NULLS [FIRST|LAST]) Returns the first row or rows from a set based on the specified sort order. If multiple rows tie as “first” then all tied rows will be returned. Used in an aggregate function.
GROUP_ID() Used in GROUP BY specification to distinguish duplicate groups
GROUPING(expr) Used to distinguish superaggregate rows from regular grouped rows when ROLLUP and CUBE are used
GROUPING_ID(expr[,expr...]) Returns the number of the GROUPING bit vector for a row
LAST ORDER BY expr [DESC|ASC] [NULLS [FIRST|LAST]) Returns the last row or rows from a set based on the specified sort order. If multiple rows tie as “last” then all tied rows will be returned. Used in an aggregate function.
MAX([DISTINCT|ALL] expr) Returns the maximum value of expr. If the DISTINCT keyword is used, duplicate rows will be excluded from the calculation.
MIN([DISTINCT|ALL] expr) Returns the minimum value of expr. If the DISTINCT keyword is used, duplicate rows will be excluded from the calculation.
PERCENTILE_CONT(expr) WITHIN GROUP (ORDER BY expr [DESC|ASC]) Given a list of values and a specified percentile ranking, returns the interpolated value of that percentile by assuming a continuous distribution of data in the list
PERCENTILE_DISC(expr) WITHIN GROUP (ORDER BY expr [DESC|ASC]) Given a list of values and a specified percentile ranking, returns the smallest value that meets or exceeds that percentile rank by assuming a discrete distribution of data in the list
PERCENT_RANK(expr) WITHIN GROUP (ORDER BY expr [DESC|ASC][NULLS FIRST|LAST]) Given a list of values, calculates the hypothetical rank of a single value within that list
RANK(expr) WITHIN GROUP (ORDER BY expr [DESC|ASC][NULLS FIRST|LAST]) Returns the rank (ordering) of expr in the group of values returned by the order by expression
STDDEV([DISTINCT|ALL] expr) Returns the standard deviation of expr
STDDEV_POP([DISTINCT|ALL] expr) Returns the square root of the population variance from computing the standard deviation of expr
STDDEV_SAMP([DISTINCT|ALL] expr) Returns the square root of the cumulative sample standard deviation of expr
SUM([DISTINCT|ALL] expr) Returns the sum of expr. Distinct eliminates duplicates from the set of values being summed.
VAR_POP(expr) Returns the population variance of expr. Nulls are removed from the calculation.
VAR_SAMP(expr) Returns the sample variance of expr. Nulls are removed from the calculation.
VARIANCE([DISTINCT|ALL] expr) The variance of expr, with duplicates removed if DISTINCT is specified

Table 1-12. Regression Functions

Function

What it does

REGR_SLOPE(expr,expr2) Returns the slope of a least squares regression line of the set of number pairs defined by (expr,expr2)
REGR_INTERCEPT(expr,expr2) Returns the Y intercept of a least squares regression line of the set of number pairs defined by (expr,expr2)
REGR_COUNT(expr,expr2) Returns the number of NOT NULL pairs used to fit the least squares regression line of the set of number pairs defined by (expr,expr2)
REGR_R2(expr,expr2) Returns the R2 value (coefficient of determination) of a least squares regression line of the set of number pairs defined by (expr,expr2)
REGR_AVGX(expr,expr2) Returns the average value of expr2 of a least squares regression line of the set of number pairs defined by (expr,expr2) after removing nulls from the calculation
REGR_AVGY(expr,expr2) Returns the average value of expr of a least squares regression line of the set of number pairs defined by (expr,expr2) after removing nulls from the calculation
REGR_SXX(expr,expr2) Returns the value of calculating REGR_COUNT(expr, expr2) * VAR_POP(expr2) with nulls removed from the calculation
REGR_SYY(expr,expr2) Returns the value of calculating REGR_COUNT(expr, expr2) * VAR_POP(expr) with nulls removed from the calculation
REGR_SXY(expr,expr2) Returns the value of calculating REGR_COUNT(expr, expr2) * COVAR_POP(expr,expr2) with nulls removed from the calculation

Analytical Functions

All of the aggregate functions described above can also have analytic functionality, using the OVER (analytical_clause) syntax. For space considerations, we've declined to list them twice. Note that you cannot nest analytic functions.

Table 1-13. Analytical Functions

Function

What it does

FIRST_VALUE(expr) OVER (analytical_clause) Returns the first in the ordered set of expr
LAG(expr[,offset][,default]) OVER (analytical_clause) Provides access at a point offset prior to the cursor in a series of rows returned by expr
LAST_VALUE(expr) OVER (analytical_clause) Returns the last in the ordered set of expr
LEAD(expr[,offset][,default]) OVER (analytical_clause) Provides access at a point offset beyond the cursor in a series of rows returned by expr
NTILE(expr) OVER (analytical_clause) Divides the ordered dataset into expr number of buckets
RATIO_TO_REPORT(expr) OVER (analytical_clause) Returns the ratio of expr to the sum returned by analytical_clause
ROW_NUMBER(expr) OVER ([partition_clause]order_by_clause) Assigns a unique number to each row

Object Reference Functions

Table 1-14. Object Reference Functions

Function

What it does

DEREF(expr) Returns the object reference of expr. Without this, an the object ID of the reference would be returned.
MAKE_REF(table|view,key [,key...]) Returns a REF to a row of an object view or table
REF(correlation_var) Returns the REF value of correlation_var
REFTOHEX(expr) Converts expr to its hexadecimal equivalent where expr is a REF
VALUE(correlation_var) Returns the value associated with the correlation_var

Date Format Models

Table 1-15. Date Format Models

Element

Value Returned

- / , . ; “text” Quoted text and punctuation are reproduced in the result
AD A.D. Indicates date that is AD. Periods optional
AM A.M. PM P.M. Before or after noon. Periods optional
BC B.C. Indicates date that is BC. Periods optional
CC SCC Century (SCC precedes BC century with -)
D The day of week (1–7)
DAY The name of the day of the week (Monday, Tuesday, etc.). Padded to 9 characters.
DD Day of month (1–31)
DDD The number of the day of year (1–366)
DY The name of the day of the week, abbreviated
E Abbreviated era name (for Japanese Imperial, ROC Official, and Thai Buddha calendars)
EE Full era name
FF [1–9] Fractional seconds. 1–9 specifies the number of digits
HH Hour of day(12-hour clock)
HH12 Hour of day (12-hour clock)
HH24 Hour of day (24-hour clock)
IW Number of Week of the year
IYY IY I Last 3, 2, or 1 digit(s) of ISO year
IYYY 4-digit ISO year
J Julian day(number of days since January 1, 4712 BC)
MI Minute (0–59)
MM Month (01–12)
MON JAN, FEB, MAR, etc.
MONTH Full month name, padded to 9 characters
Q Quarter of year where JAN–MAR = 1
RM Month in Roman numerals (I–XII; JAN = I)
RR Last two digits of the year, for years in previous or next century (where previous if current year is <=50, next if current year >50)
RRRR Round year. Accepts 4 or 2 digit input, 2 digit returns as RR.
SS Seconds (0–59)
SSSSS Seconds past midnight (0–86399)
TZD Abbreviated Time Zone String with Daylight Savings
TZH Time zone hour
TZM Time zone minute
WW The week of the year (1–53)
W The week of the month
X Local radix character
Y, YYY Year, with comma as shown
YEAR
SYEAR
Year, fully spelled out. For SYEAR, BC dates use “-”
Y
YY
YYY
Final one, two, or three digits of the year

Date Prefixes and Suffixes

The following prefixes can be added to date formats:

FM The fill mode toggle. Suppresses blank padding of MONTH or DAY
FX Specifies that the format of TO_DATE functions must be an exact match

The following suffixes may be added to date formats:

TH converts to an ordinal number ("5TH")
SP Spells out the number ("FIVE")
SPTH or THSP Spells out the ordinal number ("FIFTH")

Number Format Models

Table 1-16. Number Format Models

Element

Example

Value Returned

, 9,999 Returns a comma at the position specified
. 99.99 Returns a period (decimal point) at the position specified
$ $9999 Leading dollar sign
0 0999 Returns value with leading zeros
0 9990 Returns value with trailing zeros
9 9999 Returns value with the specified number of digits. Leading space if positive, – if negative. Leading zeros are blank, except when integer portion is zero, then a single leading zero is returned.
B B9999 As in 9, above, but returns a blank in all cases for leading zeros
C C999 Returns the ISO currency symbol
D 99D99 Returns the NLS decimal character in the specified position
EEEE 9.9EEEE Returns value in scientific notation
FM FM90.9 Returns a value without leading or trailing blanks
G 9G999 Returns the value with the NLS group separator in the specified position
L L999 Returns the value with the NLS Local Currency Symbol in the specified position. Negative values have a trailing minus sign (–), positive values with a trailing blank.
PR 9999PR Returns negative values in <angle brackets>, positives have leading and trailing blanks
RN rn RN rn Returns the value as Roman numerals, in the case-specified
S S9999 9999S Returns the value with a + or – sign denoting positive or negative value in the position shown (can only be first or last position).
TM TM “Text minimum.” Returns the smallest number of characters possible and is case-insensitive. Default is TM9 that uses fixed notation up to 64 characters, then scientific notation.
U U9999 Returns the “Euro” (or other) NLS dual currency symbol in the specified position
V 999V99 Returns a value multiplied by 10 times the number of 9s specified after the V
X XXXX Returns the Hexadecimal value. Precede with a 0 to have leading zeros, or FM to remove the leading blank.


NULL - Related Functions
The examples will require the following table.

DROP TABLE null_test_tab;
CREATE TABLE null_test_tab (
  id   NUMBER,
  col1 VARCHAR2(10),
  col2 VARCHAR2(10),
  col3 VARCHAR2(10),
  col4 VARCHAR2(10)
);

INSERT INTO null_test_tab values (1, 'ONE', 'TWO', 'THREE', 'FOUR');
INSERT INTO null_test_tab values (2, NULL, 'TWO', 'THREE', 'FOUR');
INSERT INTO null_test_tab values (3, NULL, NULL, 'THREE', 'FOUR');
INSERT INTO null_test_tab values (4, NULL, NULL, 'THREE', 'THREE');
COMMIT;

NVL
The NVL function allows you to replace null values with a default value. If the value in the first parameter is null, the function returns the value in the second parameter.
If the first parameter is any value other than null, it is returned unchanged.
We know that COL1 in the test table contains null in all rows except the first. Using the NVL function we replace the null values with 'ZERO'.

SELECT id, NVL(col1, 'ZERO') AS output FROM null_test_tab ORDER BY id;

        ID OUTPUT
---------- ----------
         1 ONE
         2 ZERO
         3 ZERO
         4 ZERO

NVL2
The NVL2 function accepts three parameters. If the first parameter value is not null it returns the value in the second parameter. If the first parameter value is null, it returns the third parameter.
The following query shows NVL2 in action.

SELECT id, NVL2(col1, col2, col3) AS output FROM null_test_tab ORDER BY id;

    ID OUTPUT
---------- ----------
           1 TWO
           2 THREE
           3 THREE
           4 THREE

The first row in the test table has a not null value in COL1, so the value of COL2 is returned. All other rows contains null in COL1, so the value of COL3 is returned.

COALESCE
The COALESCE function was introduced in Oracle 9i. It accepts two or more parameters and returns the first non-null value in a list. If all parameters contain null values, it returns null.

SELECT id, COALESCE(col1, col2, col3) AS output FROM null_test_tab ORDER BY id;

        ID OUTPUT
---------- ----------
         1 ONE
         2 TWO
         3 THREE
         4 THREE


NULLIF
The NULLIF function was introduced in Oracle 9i. It accepts two parameters and returns null if both parameters are equal. If they are not equal, the first parameter value is returned.
In our test table the values of COL3 and COL4 are equal in row 4, so we would only expect null returned for that row using the following query.

SELECT id, NULLIF(col3, col4) AS output FROM null_test_tab ORDER BY id;

        ID OUTPUT
---------- ----------
         1 THREE
         2 THREE
         3 THREE
         4