MetaData Class

A MetaData object can be used to describe the types and properties of the columns in a ResultSet or the existing schema objects in the database. It also provides information about the database as a whole. The enumerated values of MetaData are in Table 12-26, and the summary of its methods is in Table 12-27.

Table 12-26 Enumerated Values Used by MetaData Class

Attribute	Options
ParamType	The parameter types for objects are: `PTYPE_ARG` is the argument of a function or procedure. `PTYPE_COL` is the column of a table or view. `PTYPE_DATABASE` is the database. `PTYPE_FUNC` is the function. `PTYPE_PKG` is the package. `PTYPE_PROC` is the procedure. `PTYPE_SCHEMA` is the schema. `PTYPE_SEQ` is the sequence. `PTYPE_SYN` is the synonym. `PTYPE_TABLE` is the table. `PTYPE_TYPE` is the type. `PTYPE_TYPE_ARG` is the argument of a type method. `PTYPE_TYPE_ATTR` is the attribute of a type. `PTYPE_TYPE_COLL` is the collection type information. `PTYPE_TYPE_METHOD` is the method of a type. `PTYPE_TYPE_RESULT` is the results of a method. `PTYPE_UNK` is the object of an unknown type. `PTYPE_VIEW` is the view.
`AttrId` common to all parameters	Attributes of all parameters: `ATTR_OBJ_ID` is the object or schema id. `ATTR_OBJ_NAME` is either the database name, or the object name in a schema. `ATTR_OBJ_SCHEMA` is the name of the schema describing the object. `ATTR_PTYPE` is the type of information described by a parameter, ParamType `ATTR_TIMESTAMP` is the timestamp of an object.
`AttrId` for Tables and Views	Parameters for a table or view (ParamType of PTYPE_TABLE and PTYPE_VIEW) have the following type-specific attributes: `ATTR_OBJID` is the object id `ATTR_NUM_COLS` is the number of columns `ATTR_LIST_COLUMNS` is the column list `ATTR_REF_TDO` is the `REF` to the `TDO` of the base type in case of extent tables `ATTR_IS_TEMPORARY` indicates the table is temporary `ATTR_IS_TYPED` indicates the table is typed `ATTR_DURATION` is the duration of a temporary table. Values can be DURATION_SESSION, DURATION_TRANS, and DURATION_NULL, as defined for attribute AttrValues
`AttrId` for Tables only	Parameters for a tables only (ParamType of PTYPE_TABLE): `ATTR_RDBA` indicates the data block address of the segment header `ATTR_TABLESPACE` indicates the tablespace the table resides in `ATTR_CLUSTERED` indicates the table is clustered `ATTR_PARTITIONED` indicates the table is partitioned `ATTR_INDEX_ONLY` indicates the table is index-only
`AttrId` for Functions and Procedures	Parameters for functions and procedures (ParamType of PTYPE_FUNC and PTYPE_PROC, respectively): `ATTR_LIST_ARGUMENTS` indicates the argument list `ATTR_IS_INVOKER_RIGHTS` indicates the procedure or function has invoker's rights `ATTR_NAME` indicates the name of the procedure or function `ATTR_OVERLOAD_ID` indicates the overloading ID number, relevant when the procedure or function is part of a class and it is overloaded; values returned may be different from direct query of a PL/SQL function or procedure
`AttrId` for Packages	Parameters for packages (ParamType of PTYPE_PKG): `ATTR_LIST_SUBPROGRAMS` indicates the subprogram list `ATTR_IS_INVOKER_RIGHTS` indicates the procedure or function has invoker's rights
`AttrId` for Types	Parameter is for types (ParamType of PTYPE_TYPE): `ATTR_REF_TDO` indicates the in-memory `REF` of the type descriptor for the type, if the column type is an object type. If space has not been reserved, then it is allocated implicitly in the cache. The caller can then pin the object. `ATTR_TYPECODE` indicates the datatype code `ATTR_COLLECTION_TYPECODE` indicates the typecode of collection, if type is collection `ATTR_IS_INCOMPLETE_TYPE` indicates that this is an incomplete type `ATTR_IS_SYSTEM_TYPE` indicates that this is a system generated type `ATTR_IS_PREDEFINED_TYPE` indicates that this is a predefined type `ATTR_IS_TRANSIENT_TYPE` indicates that this is a transient type `ATTR_IS_SYSTEM_GENERATED_TYPE` indicates that this is a system generated type `ATTR_HAS_NESTED_TABLE` indicates that this type contains a nested table attribute `ATTR_HAS_LOB` indicates that this type contains a `LOB` attribute `ATTR_HAS_FILE` indicates that this type contains a `BFILE` attribute `ATTR_COLLECTION_ELEMENT` indicates a reference to a collection element `ATTR_NUM_TYPE_ATTRS` indicates the number of type attributes `ATTR_LIST_TYPE_ATTRS` indicates the list of type attributes `ATTR_NUM_TYPE_METHODS` indicates the number of type methods `ATTR_LIST_TYPE_METHODS` indicates the list of type methods `ATTR_MAP_METHOD` indicates the map method of the type `ATTR_ORDER_METHOD` indicates the order method of the type `ATTR_IS_INVOKER_RIGHTS` indicates the type has invoker's rights `ATTR_NAME` indiccates the type attribute name `ATTR_SCHEMA_NAME` indicates the schema where the type is created `ATTR_IS_FINAL_TYPE` indicates this is a final type `ATTR_IS_INSTANTIABLE_TYPE` indicates this is an instantiable type `ATTR_IS_SUBTYPE` indicates this is a subtype `ATTR_SUPERTYPE_SCHEMA_NAME` indicates the name of the schema that contains the supertype `ATTR_SUPERTYPE_NAME` indicates the name of the supertype
`AttrId` for Type Attributes	Parameter is for attributes of types (ParamType of PTYPE_TYPE_ATTR): `ATTR_DATA_SIZE` indicates the maximum size of the type attribute `ATTR_TYPECODE` indicates the datatype code `ATTR_DATA_TYPE` indicates the datatype of the type attribute `ATTR_NAME` indicates the name of the procedure or function `ATTR_PRECISION` indicates the precision of numeric type attributes. `ATTR_SCALE` indicates the scale of the numeric type attributes `ATTR_TYPE_NAME` indicates a type name `ATTR_SCHEMA_NAME` indicates the name of the schema where the type has been created `ATTR_REF_TDO` indicates the in-memory `REF` of the type, if the column type is an object type. If the space has not been reserved, it is allocated implicityly in the cache. The caller can then pin the object. `ATTR_CHARSET_ID` indicates the characterset ID `ATTR_CHARSET_FORM` indicates the characterset form `ATTR_FSPRECISION` indicates the fractional seconds precision of a `Timestamp`, `IntervalDS` or `IntervalYM` `ATTR_LFPRECISION` indicates the leading field precision of an `IntervalDS` or `IntervalYM`
`AttrId` for Type Methods	Parameter is for methods of types (ParamType of PTYPE_TYPE_METHOD): `ATTR_NAME` indicates the name of the procedure or function `ATTR_ENCAPSULATION` indicates the method's level of encapsulation `ATTR_LIST_ARGUMENTS` indicates the argument list `ATTR_IS_CONSTRUCTOR` indicates the method is a constructor `ATTR_IS_DESTRUCTOR` indicates the method is a destructor `ATTR_IS_OPERATOR` indicates the method is an operator `ATTR_IS_SELFISH` indicates the method is selfish `ATTR_IS_MAP` indicates the method is a map method `ATTR_IS_ORDER` indicates the method is an order method `ATTR_IS_RNDS` indicates that the method is in "read no data" state `ATTR_IS_RNPS` indicates that the method is in a "read no process" state `ATTR_IS_WNDS` indcates that the method is in "write no data" state `ATTR_IS_WNPS` indicates that the method is in "write no process" state `ATTR_IS_FINAL_METHOD` indicates that this is a final method `ATTR_IS_INSTANTIABLE_METHOD` indicates that this is an instantiable method `ATTR_IS_OVERRIDING_METHOD` indicates that this is an overriding method
`AttrId` for Collections	Parameter is for collections (ParamType of PTYPE_TYPE_COLL): `ATTR_DATA_SIZE` indicates `ATTR_TYPECODE` indicates `ATTR_DATA_TYPE` indicates the datatype of the type attribute `ATTR_NUM_ELEMS` indicates the number of elements in a collection `ATTR_NAME` indicates the name of the type attribute `ATTR_PRECISION` indicates the precision of a numeric attribute `ATTR_SCALE` indicates the scale of a numberic attribute `ATTR_TYPE_NAME` indicates the type name `ATTR_SCHEMA_NAME` indicates the schema where the type has been created `ATTR_REF_TDO` indicates the in-memory `REF` of the type, if the column type is an object type. If the space has not been reserved, it is allocated implicityly in the cache. The caller can then pin the object. `ATTR_CHARSET_ID` indicates the characterset id `ATTR_CHARSET_FORM` indicates the characterset form
`AttrId` for Synonyms	Parameter is for synonyms (ParamType of PTYPE_SYN): `ATTR_OBJID` indicates the object id `ATTR_SCHEMA_NAME` indicates the schema name of the synonym translation `ATTR_NAME` indicates indicates a `NULL`-terminated object name of the synonym translation `ATTR_LINK` indicates a `NULL-`terminated database link name of the synonym installation
`AttrId` for Sequences	Parameter is for sequences (ParamType of PTYPE_SEQ): `ATTR_OBJID` indicates the object id `ATTR_MIN` indicates the minimum value `ATTR_MAX` indicates the maximum value `ATTR_INCR` indicates the increment `ATTR_CACHE` indicates the number of sequence numbers cached; 0 if the sequence is not cahced `ATTR_ORDER` indicates whether the sequence is ordered `ATTR_HW_MARK` indicates the "high-water mark"
`AttrId` for Columns	Parameter is for columns of tables or views (ParamType of PTYPE_COL): `ATTR_CHAR_USED` indicates the type of length semantics of the column. `0` means byte-length semanitcs and `1` means character-length semantics. `ATTR_CHAR_SIZE` indicates the column character length, or number of characters allowed in a column `ATTR_DATA_SIZE` indicates the maximum size of a column , or number of bytes allowed in a column `ATTR_DATA_TYPE` indicates the dtatype of the column `ATTR_NAME` indicates indicates the column name `ATTR_PRECISION` indicates the precision of numeric columns `ATTR_SCALE` indicates indicates the scale of numeric columns `ATTR_IS_NULL` indicates `0` if `NULL` values are not permitted for the column `ATTR_TYPE_NAME` indicates a type name `ATTR_SCHEMA_NAME` indicates the schema where the type was created `ATTR_REF_TDO` indicates the `REF` for the type, if the colum is of object type `ATTR_CHARSET_ID` indicates the characterset ID `ATTR_CHARSET_FORM` indicates the characterset form
`AttrId` for Arguments and Results	Parameter for arguments of a procedure or function (PTYPE_ARG), a method (PTYPE_TYPE_ARG), or a result (PTYPE_TYPE_RESULT) `ATTR_NAME` indicates the argument name `ATTR_POSITION` indicates the position of the argument in the list `ATTR_TYPECODE` indicates the typecode `ATTR_DATA_TYPE` indicates the datatype `ATTR_DATA_SIZE` indicates the size of the datatype `ATTR_PRECISION` indicates the precision of a numeric argument `ATTR_SCALE` indicates the scale of a numeric argument `ATTR_LEVEL` indicates the datatype level `ATTR_HAS_DEFAULT` indicates whether an argument has a default `ATTR_LIST_ARGUMENTS` indicates the list of arguments at the next level, for records or table types `ATTR_IOMODE` indicates the argument mode: `0` for `IN`, `1` for `OUT`, `2` for `IN/OUT` `ATTR_RADIX` indicates the radix of a number type `ATTR_IS_NULL` indicates `0` if `NULL` values are not permitted `ATTR_TYPE_NAME` indicates the type name `ATTR_SCHEMA_NAME` indicates the schema name where the type was created `ATTR_SUB_NAME` indicates the type name for packate local types `ATTR_LINK` indicates a `NULL-`terminated database link name where the type is defined, for package local types when the package is remote `ATTR_REF_TDO` is the `REF` to the `TDO` of the type if the argument is an object `ATTR_CHARSET_ID` indicates the characterset ID `ATTR_CHARSET_FORM` indicates the characterset form
`AttrId` for Schemas	Parameter is for schemas (ParamType of PTYPE_SCHEMA): `ATTR_LIST_OBJECTS` indicates the list of objects in the schema
`AttrId` for Lists	Parameter is for list of columns, arguments or subprograms: `ATTR_LIST_COLUMNS` indicates a column list `ATTR_LIST_ARGUMENTS` indicates a procedure or function argument list `ATTR_LIST_SUBPROGRAMS` indicates a subprogram list `ATTR_LIST_TYPE_ATTRIBS` indicates a type attribute list `ATTR_TYPE_METHODS` indicates a type method list `ATTR_TYPE_OBJECTS` indicates a list of objects in a shcema `ATTR_LIST_SCHEMAS` indicates a list of schemas in a database
`AttrId` for Databases	Parameter is for list of columns, arguments or subprograms (ParamType of PTYPE_DATABASE): `ATTR_VERSION` indicates the database version `ATTR_CHARSET_ID` indicates the characterset ID of the database `ATTR_NCHARSET_ID` indicates the national characterset of the database `ATTR_LIST_SCHEMAS` indicates the list of schemas, PTYPE_SCHEMA `ATTR_MAX_PROC_LEN` indicates the maximum length of a procedure name `ATTR_MAX_COLUMN_LEN` indicates the maximum length of a column name `ATTR_CURSOR_COMMIT_BEHAVIOR` indicates how a commit affects cursors and prepared statements. Values can be CURSOR_OPEN and CURSER_CLOSED, as defined for attribute AttrValues `ATTR_MAX_CATALOG_NAMELEN` indicates the maximum length of a database (catalog) name `ATTR_CATALOG_LOCATION` indicates the position of the catalog in a qualified table. Values can be CL_START and CL_END, as defined for attribute AttrValues `ATTR_SAVEPOINT_SUPPORT` indicates whether the database supports savepoints. Values can be SP_SUPPORTED and SP_UNSUPPORTED, as defined for attribute AttrValues `ATTR_NOWAIT_SUPPORT` indicates whether the database suports the "no wait" condition. Values can be NW_SUPPORTED and NW_UNSUPPORTED, as defined for attribute AttrValues `ATTR_AUTOCOMMIT_DDL` indicates if an autocommit mode is required for DDL statements. Values can be AC_DDL and NO_AC_DDL, as defined for attribute AttrValues `ATTR_LOCKING_MODE` indicates the locking mode for the database. Values can be LOCK_IMMEDIATE and LOCK_DELAYED, as defined for attribute AttrValues
AttrValues	Attribute values are returned on executing a `getxxx()` method and passing in an attribute, for which these are the results: `DURATION_SESSION` is the duration of a temporary table: session. `DURATION_TRANS` is the duration of a temporary table: transaction. `DURATION_NULL` is the duration of a temporary table: table not temporary. `TYPEENCAP_PRIVATE` is the encapsulation level of the method: private. `TYPEENCAP_PUBLIC` is the encapsulation level of the method: public. `TYPEPARAM_IN` is the argument mode: `IN`. `TYPEPARAM_OUT` is the argument mode: `OUT`. `TYPEPARAM_INOUT` is the argument mode: `IN/OUT`. `CURSOR_OPEN` is the effect of `COMMIT` operation on cursors and prepared statements in the database: preserve cursor state as before the `COMMIT` operation. `CURSER_CLOSED` is the effect of `COMMIT` operation on cursors and prepared statements in the database: cursors are closed on `COMMIT`, but the applicaton can still rerun the statement without preparing it again. `CL_START` is the position of the catalog in a qualified table: start. `CL_END` is the position of the catalog in a qualified table: end. `SP_SUPPORTED` is the database supports savepoints. `SP_UNSUPPORTED` is the database does not support savepoints. `NW_SUPPORTED` is the database supports nowait clause. `NW_UNSUPPORTED` is the database does not supports nowait clause. `AC_DDL` is the autocommit mode required for DDL statements. `NO_AC_DDL` is the autocommit mode not required for DDL statements. `LOCK_IMMEDIATE` is the locking mode for the database: immediate. `LOCK_DELAYED` is the locking mode for the database: delayed.

Table 12-27 Summary of MetaData Methods

Method	Description
MetaData()	`MetaData` class constructor.
getAttributeCount()	Gets the count of the attribute as a `MetaData` object
getAttributeId()	Gets the ID of the specified attribute
getAttributeType()	Gets the type of the specified attribute.
getBoolean()	Gets the value of the attribute as a C++ `boolean`.
getInt()	Gets the value of the attribute as a C++ `int`.
getMetaData()	Gets the value of the attribute as a `MetaData` object
getNumber()	Returns the specified attribute as a `Number` object.
getRef()	Gets the value of the attribute as a `Ref<T>`.
getString()	Gets the value of the attribute as a string.
getTimeStamp()	Gets the value of the attribute as a `Timestamp` object
getUInt()	Gets the value of the attribute as a C++ `unsigned int`.
getUString()	Returns the value of the attribute as a `UString` in the character set associated with the metadata.
getVector()	Gets the value of the attribute as an C++ vector.
operator=()	Assigns one metadata object to another.

MetaData()

MetaData class constructor.

Syntax

MetaData(
   const MetaData &omd);

Parameter	Description
cmd	The source that the `MetaData` object will be copied from.

getAttributeCount()

This method returns the number of attributes related to the metadata object.

Syntax

unsigned int getAttributeCount() const;

getAttributeId()

This method returns the attribute ID (ATTR_NUM_COLS, . . . ) of the attribute represented by the attribute number specified.

Syntax

AttrId getAttributeId(
   unsigned int attributeNum) const;

Parameter	Description
attributeNum	The number of the attribute for which the attribute ID is to be returned.

getAttributeType()

This method returns the attribute type (NUMBER, INT, . . . ) of the attribute represented by attribute number specified.

Syntax

Type getAttributeType(
   unsigned int attributeNum) const;

Parameter	Description
attributeNum	The number of the attribute for which the attribute type is to be returned.

getBoolean()

This method returns the value of the attribute as a C++ boolean. If the value is a SQL NULL, the result is FALSE.

Syntax

bool getBoolean(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getInt()

This method returns the value of the attribute as a C++ int. If the value is SQL NULL, the result is 0.

Syntax

int getInt(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getMetaData()

This method returns a MetaData instance holding the attribute value. A metadata attribute value can be retrieved as a MetaData instance. This method can only be called on attributes of the metadata type.

Syntax

MetaData getMetaData(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getNumber()

This method returns the value of the attribute as a Number object. If the value is a SQL NULL, the result is NULL.

Syntax

Number getNumber(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getRef()

This method returns the value of the attribute as a RefAny, or Ref to a TDO. If the value is SQL NULL, the result is NULL.

Syntax

RefAny getRef(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getString()

This method returns the value of the attribute as a string. If the value is SQL NULL, the result is NULL.

Syntax

string getString(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getTimeStamp()

This method returns the value of the attribute as a Timestamp object. If the value is a SQL NULL, the result is NULL.

Syntax

Timestamp getTimestamp(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getUInt()

This method returns the value of the attribute as a C++ unsigned int. If the value is a SQL NULL, the result is 0.

Syntax

unsigned int getUInt(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getUString()

Returns the value of an attribute as a UString in the character set associated with the metadata.

Syntax

UString getUString(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

getVector()

This method returns a C++ vector containing the attribute value. A collection attribute value can be retrieved as a C++ vector instance. This method can only be called on attributes of a list type.

Syntax

vector<MetaData> getVector(
   MetaData::AttrId attributeId) const;

Parameter	Description
attributeId	The attribute ID

operator=()

This method assigns one MetaData object to another. This increments the reference count of the MetaData object that is assigned.

Syntax

void operator=(
   const MetaData &omd);

Parameter	Description
cmd	MetaData object to be assigned