MySQL 8.4 Release Notes
PARAMETERS 表提供存储例程（存储过程和存储函数）参数以及存储函数的返回值的信息。PARAMETERS 表不包括内置（本地）函数或可加载函数。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.
PARAMETERS 表有以下列：The PARAMETERS table has these
columns:
SPECIFIC_CATALOG包含该参数的例程所属目录的名称。该值始终为
def。The name of the catalog to which the routine containing the parameter belongs. This value is alwaysdef.SPECIFIC_SCHEMA包含该参数的例程所属的模式（数据库）名称。The name of the schema (database) to which the routine containing the parameter belongs.
SPECIFIC_NAME包含该参数的例程名称。The name of the routine containing the parameter.
ORDINAL_POSITION对于存储过程或函数的连续参数，
ORDINAL_POSITION的值分别为 1、2、3，以此类推。对于存储函数，还有一行适用于函数返回值（如RETURNS子句所描述）。返回值不是一个真正的参数，因此描述它的行具有以下独特特征：For successive parameters of a stored procedure or function, theORDINAL_POSITIONvalues 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 theRETURNSclause). The return value is not a true parameter, so the row that describes it has these unique characteristics:ORDINAL_POSITION值为 0。TheORDINAL_POSITIONvalue is 0.PARAMETER_NAME和PARAMETER_MODE的值为NULL，因为返回值没有名称且模式不适用。ThePARAMETER_NAMEandPARAMETER_MODEvalues areNULLbecause the return value has no name and the mode does not apply.
PARAMETER_MODE参数的模式。此值为
IN、OUT或INOUT之一。对于存储函数的返回值，此值为NULL。The mode of the parameter. This value is one ofIN,OUT, orINOUT. For a stored function return value, this value isNULL.PARAMETER_NAME参数的名称。对于存储函数的返回值，此值为
NULL。The name of the parameter. For a stored function return value, this value isNULL.DATA_TYPE参数的数据类型。The parameter data type.
DATA_TYPE的值仅为类型名称，不包含其他信息。DTD_IDENTIFIER的值包含类型名称及可能的其他信息，如精度或长度。TheDATA_TYPEvalue is the type name only with no other information. TheDTD_IDENTIFIERvalue contains the type name and possibly other information such as the precision or length.CHARACTER_MAXIMUM_LENGTH对于字符串参数，最大字符长度。For string parameters, the maximum length in characters.
CHARACTER_OCTET_LENGTH对于字符串参数，最大字节长度。For string parameters, the maximum length in bytes.
NUMERIC_PRECISION对于数字参数，数值精度。For numeric parameters, the numeric precision.
NUMERIC_SCALE对于数字参数，数字刻度。For numeric parameters, the numeric scale.
DATETIME_PRECISION对于时间参数，分秒精度。For temporal parameters, the fractional seconds precision.
CHARACTER_SET_NAME对于字符字符串参数，字符集名称。For character string parameters, the character set name.
COLLATION_NAME对于字符字符串参数，排序规则名称。For character string parameters, the collation name.
DTD_IDENTIFIER参数的数据类型。The parameter data type.
DATA_TYPE的值仅为类型名称，不包含其他信息。DTD_IDENTIFIER的值包含类型名称及可能的其他信息，如精度或长度。TheDATA_TYPEvalue is the type name only with no other information. TheDTD_IDENTIFIERvalue contains the type name and possibly other information such as the precision or length.ROUTINE_TYPEPROCEDURE对于存储过程，FUNCTION对于存储函数。PROCEDUREfor stored procedures,FUNCTIONfor stored functions.