Library: Data
Package: DataCore
Header: Poco/Data/ODBC/Preparation.h
Description
Class used for database preparation where we first have to register all data types with respective memory output locations before extracting data. Extraction works in two-phases: first prepare is called once, then extract n-times. In ODBC, SQLBindCol/SQLFetch is the preferred method of data retrieval (SQLGetData is available, however with numerous driver implementation dependent limitations). In order to fit this functionality into Poco DataConnectors framework, every ODBC SQL statement instantiates its own Preparation object. This is done once per statement execution (from StatementImpl::bindImpl()).
Preparation object is used to :
1) Prepare SQL statement. 2) Provide and contain the memory locations where retrieved values are placed during recordset iteration. 3) Keep count of returned number of columns with their respective datatypes and sizes.
Notes:
- Value datatypes in this interface prepare() calls serve only for the purpose of type distinction. - Preparation keeps its own std::vector<Any> buffer for fetched data to be later retrieved by Extractor. - prepare() methods should not be called when extraction mode is DE_MANUAL
Inheritance
Direct Base Classes: Poco::Data::AbstractPreparation
All Base Classes: Poco::Data::AbstractPreparation, Poco::RefCountedObject
Member Summary
Member Functions: actualDataSize, columns, getDataExtraction, getMaxFieldSize, maxDataSize, operator, prepare, setDataExtraction, setMaxFieldSize
Inherited Functions: duplicate, prepare, referenceCount, release
Enumerations
DataExtraction
Constructors
Preparation
Preparation(
const StatementHandle & rStmt,
const std::string & statement,
std::size_t maxFieldSize,
DataExtraction dataExtraction = DE_BOUND
);
Creates the Preparation.
Destructor
~Preparation 
~Preparation();
Destroys the Preparation.
Member Functions
actualDataSize 
std::size_t actualDataSize(
std::size_t pos
) const;
Returns the returned length. This is usually equal to the column size, except for variable length fields (BLOB and variable length strings).
columns
std::size_t columns() const;
Returns the number of columns.
getDataExtraction
DataExtraction getDataExtraction() const;
Returns data extraction mode.
getMaxFieldSize
std::size_t getMaxFieldSize() const;
maxDataSize
std::size_t maxDataSize(
std::size_t pos
) const;
Returns max supported size for column at position pos. Returned length for variable length fields is the one supported by this implementation, not the underlying DB.
operator
Poco::Any & operator[] (
std::size_t pos
);
Returns reference to column data.
prepare
void prepare(
std::size_t pos,
Poco::Int8
);
Prepares an Int8.
prepare
void prepare(
std::size_t pos,
Poco::UInt8
);
Prepares an UInt8.
prepare
void prepare(
std::size_t pos,
Poco::Int16
);
Prepares an Int16.
prepare
void prepare(
std::size_t pos,
Poco::UInt16
);
Prepares an UInt16.
prepare
void prepare(
std::size_t pos,
Poco::Int32
);
Prepares an Int32.
prepare
void prepare(
std::size_t pos,
Poco::UInt32
);
Prepares an UInt32.
prepare
void prepare(
std::size_t pos,
Poco::Int64
);
Prepares an Int64.
prepare
void prepare(
std::size_t pos,
Poco::UInt64
);
Prepares an UInt64.
prepare
void prepare(
std::size_t pos,
bool
);
Prepares a boolean.
prepare
void prepare(
std::size_t pos,
float
);
Prepares a float.
prepare
void prepare(
std::size_t pos,
double
);
Prepares a double.
prepare
void prepare(
std::size_t pos,
char
);
Prepares a single character.
prepare
void prepare(
std::size_t pos,
const std::string & param32
);
Prepares a string.
prepare
void prepare(
std::size_t pos,
const Poco::Data::BLOB & param33
);
Prepares a BLOB.
prepare
void prepare(
std::size_t pos,
const Poco::Any & param34
);
Prepares an Any.
setDataExtraction
void setDataExtraction(
DataExtraction ext
);
Set data extraction mode.
setMaxFieldSize
void setMaxFieldSize(
std::size_t size
);
Sets maximum supported field size.