28.3.20 INFORMATION_SCHEMA PARAMETERS 表
The PARAMETERS
table provides information about parameters for stored routines (stored procedures and stored functions), and about return values for stored functions. The PARAMETERS
table does not include built-in (native) functions or loadable functions.
The PARAMETERS
table has these columns:
-
SPECIFIC_CATALOG
The name of the catalog to which the routine containing the parameter belongs. This value is always
def
. -
SPECIFIC_SCHEMA
The name of the schema (database) to which the routine containing the parameter belongs.
-
SPECIFIC_NAME
The name of the routine containing the parameter.
-
ORDINAL_POSITION
For successive parameters of a stored procedure or function, the
ORDINAL_POSITION
values are 1, 2, 3, and so forth. For a stored function, there is also a row that applies to the function return value (as described by theRETURNS
clause). The return value is not a true parameter, so the row that describes it has these unique characteristics:-
The
ORDINAL_POSITION
value is 0. -
The
PARAMETER_NAME
andPARAMETER_MODE
values areNULL
because the return value has no name and the mode does not apply.
-
-
PARAMETER_MODE
The mode of the parameter. This value is one of
IN
,OUT
, orINOUT
. For a stored function return value, this value isNULL
. -
PARAMETER_NAME
The name of the parameter. For a stored function return value, this value is
NULL
. -
DATA_TYPE
The parameter data type.
The
DATA_TYPE
value is the type name only with no other information. TheDTD_IDENTIFIER
value contains the type name and possibly other information such as the precision or length. -
CHARACTER_MAXIMUM_LENGTH
For string parameters, the maximum length in characters.
-
CHARACTER_OCTET_LENGTH
For string parameters, the maximum length in bytes.
-
NUMERIC_PRECISION
For numeric parameters, the numeric precision.
-
NUMERIC_SCALE
For numeric parameters, the numeric scale.
-
DATETIME_PRECISION
For temporal parameters, the fractional seconds precision.
-
CHARACTER_SET_NAME
For character string parameters, the character set name.
-
COLLATION_NAME
For character string parameters, the collation name.
-
DTD_IDENTIFIER
The parameter data type.
The
DATA_TYPE
value is the type name only with no other information. TheDTD_IDENTIFIER
value contains the type name and possibly other information such as the precision or length. -
ROUTINE_TYPE
PROCEDURE
for stored procedures,FUNCTION
for stored functions.