GREATEST
The GREATEST
function returns the greatest of the list of one or more expressions.
SQL syntax
GREATEST (Expression [,...])
Parameters
GREATEST
has the parameter:
Parameter | Description |
---|---|
|
List of one or more expressions that is evaluated to determine the greatest expression value. Operand or column can be numeric, character or date. Each expression in the list must be from the same data type family. |
Description
-
Each expression in the list must be from the same data type family or date subfamily. Data type families include numeric, character and date. The date family includes four subfamilies: date family,
TIME
family,TT_DATE
family, andTT_TIMESTAMP
family. As an example, do not specify a numeric expression and a character expression in the list of expressions. Similarly, do not specify a date expression and aTT_TIMESTAMP
expression in the list of expressions. -
If the first
Expression
is numeric, then TimesTen determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that data type before the comparison, and returns that data type. -
If the first
Expression
is in the character family, and the operand or column is of typeCHAR
orVARCHAR2
, the data type returned isVARCHAR2
. If the operand or column is of typeNCHAR
orNVARCHAR2
, the data type returned isNVARCHAR2
. The returned data type length is equal to the length of the largest expression. If one operand or column is of typeCHAR
orVARCHAR2
and the second operand or column is of typeNCHAR
orNVARCHAR2
, the data type returned isNVARCHAR2
. -
TimesTen uses nonpadded comparison semantics for data types from the character family.
-
If the first expression is in the date family, the data type returned is the same data type as the first expression.
-
If any of the expressions is
NULL
, the result isNULL
. -
If the first
Expression
is in the character family, and the operand or column is of typeTT_CHAR
orTT_VARCHAR
, the data type returned isTT_VARCHAR
. If the operand or column is of typeTT_NCHAR
orTT_NVARCHAR
, the data type returned isTT_NVARCHAR
. The returned data type length is equal to the largest of the expressions. -
You can specify a maximum of 256 expressions.
Use the GREATEST
function to return the string with the greatest value:
Command> SELECT GREATEST ('GREAT', 'GREATER', 'GREATEST') FROM dual; < GREATEST > 1 row found.
Use the GREATEST
function to return the numeric expression with the greatest value. In this example, BINARY_DOUBLE
is the data type with the highest numeric precedence, so arguments are implicitly converted to BINARY_DOUBLE
before the comparison and the data type BINARY_DOUBLE
is returned:
Command> SELECT GREATEST (10, 10.55, 10.1D) FROM dual; < 10.5500000000000 > 1 row found.
Use the DESCRIBE
command to confirm the data type returned is BINARY_DOUBLE
:
Command> DESCRIBE SELECT GREATEST (10, 10.55, 10.1D) FROM dual; Prepared Statement: Columns: EXP BINARY_DOUBLE NOT NULL
Use the GREATEST
function to return the DATE
expression with the greatest value. DATE
and TIMESTAMP
are in the same date family.
Command> SELECT GREATEST (DATE '2007-09-30',TIMESTAMP '2007-09-30:10:00:00') FROM dual; < 2007-09-30 10:00:00 > 1 row found.
Attempt to use the GREATEST
function to return the greatest value in the list of TT_DATE
and TT_TIMESTAMP
expressions. You see an error because TT_DATE
and TT_TIMESTAMP
are in different date subfamilies and cannot be used in the same list of expressions.
Command> SELECT GREATEST (TT_DATE '2007-09-30', TT_TIMESTAMP '2007-09-30:10:00:00') FROM dual; 2817: Invalid data type TT_TIMESTAMP for argument 2 for function GREATEST The command failed.
Use the GREATEST
function to return the TT_DATE
expression with the greatest value.
Command> SELECT GREATEST (TT_DATE '2007-09-30', TT_DATE '2007-09-29', TT_DATE '2007-09-28') FROM dual; < 2007-09-30 > 1 row found.