| Functions, like operators, act on data to return a result. However, unlike operators, functions can operate on zero, one, or more arguments. Of the built in SQL functions in Oracle 9i, there are single row functions, aggregate functions, analytical functions and object reference functions. User defined functions, that can be written in PL/SQL or Java in Oracle 9i, are not covered here. 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 e n | | 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 n th 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] ) also: SUBSTRB - bytes SUBSTRC - unicode SUBSTR2 - UCS2 codepoints SUBSTR4 - UCS4 codepoints | 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) | | 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( [[LEADINGTRAILINGBOTH] [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]] ) also: INSTRB - bytes INSTRC - unicode INSTR2 - UCS2 codepoints INSTR4 - UCS4 codepoints | "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 ) also: LENGTHB - bytes LENGTHC - unicode LENGTH2 - UCS2 codepoints LENGTH4 - UCS4 codepoints | 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_colchar) | 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 s earch. 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 expr1 and 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( colattr [rowid][,colattr [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( [DISTINCTALL] 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(* [DISTINCTALL] 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 [DESCASC] [NULLS [FIRSTLAST]) | 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 [DESCASC] [NULLS [FIRSTLAST] ) | 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 [DESCASC] [NULLS [FIRSTLAST] ) | 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( [DISTINCTALL] expr ) | Returns the maximum value of expr . If the DISTINCT keyword is used, duplicate rows will be excluded from the calculation. | | MIN( [DISTINCTALL] 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 [DESCASC] ) | 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 [DESCASC] ) | 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 [DESCASC][NULLS FIRSTLAST] ) | Given a list of values, calculates the hypothetical rank of a single value within that list | | RANK( expr ) WITHIN GROUP ( ORDER BY expr [DESCASC][NULLS FIRSTLAST] ) | Returns the rank (ordering) of expr in the group of values returned by the order by expression | | STDDEV([DISTINCTALL] expr) | Returns the standard deviation of expr | | STDDEV_POP( [DISTINCTALL] expr ) | Returns the square root of the population variance from computing the standard deviation of expr | | STDDEV_SAMP( [DISTINCTALL] expr ) | Returns the square root of the cumulative sample standard deviation of expr | | SUM( [DISTINCTALL] 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( [DISTINCTALL] 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 ) | | R EGR_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 R 2 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( tableview,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 |  |
