4.15 The INFORMATION_SCHEMA PARAMETERS Table

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. Parameter information is similar to the contents of the param_list column in the mysql.proc table.

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 the RETURNS 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 and PARAMETER_MODE values are NULL 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, or INOUT. For a stored function return value, this value is NULL.

• 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. The DTD_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. The DTD_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.