CPLODBCStatement Class Reference

Abstraction for statement, and resultset. More...

#include <cpl_odbc.h>

Public Types
enum	Flag { RetrieveNumericColumnsAsDouble = 1 << 0 }
	Flags which control ODBC statement behavior. More...

Public Member Functions
	CPLODBCStatement (CPLODBCSession *, int flags=0)
	Constructor.
	~CPLODBCStatement ()
	Destructor.
HSTMT	GetStatement ()
	Return statement handle.
int	Flags () const
	Returns statement flags.
void	Clear ()
	Clear internal command text and result set definitions.
void	AppendEscaped (const char *)
	Append text to internal command.
void	Append (const char *)
	Append text to internal command.
void	Append (const std::string &)
	Append text to internal command.
void	Append (int)
	Append to internal command.
void	Append (double)
	Append to internal command.
int	Appendf (const char *,...)
	Append to internal command.
const char *	GetCommand ()
	Return statement string.
int	ExecuteSQL (const char *=nullptr)
	Execute an SQL statement.
int	Fetch (int nOrientation=SQL_FETCH_NEXT, int nOffset=0)
	Fetch a new record.
void	ClearColumnData ()
	ClearColumnData.
int	GetColCount ()
	Fetch the resultset column count.
const char *	GetColName (int)
	Fetch a column name.
short	GetColType (int)
	Fetch a column data type.
const char *	GetColTypeName (int)
	Fetch a column data type name.
short	GetColSize (int)
	Fetch the column width.
short	GetColPrecision (int)
	Fetch the column precision.
short	GetColNullable (int)
	Fetch the column nullability.
const char *	GetColColumnDef (int)
	Fetch a column default value.
int	GetColId (const char *) const
	Fetch column index.
const char *	GetColData (int, const char *=nullptr)
	Fetch column data.
const char *	GetColData (const char *, const char *=nullptr)
	Fetch column data.
int	GetColDataLength (int)
	GetColDataLength.
double	GetColDataAsDouble (int) const
	Fetch column data as a double value.
double	GetColDataAsDouble (const char *) const
	Fetch column data as a double value.
int	GetRowCountAffected ()
	GetRowCountAffected.
int	GetColumns (const char *pszTable, const char *pszCatalog=nullptr, const char *pszSchema=nullptr)
	Fetch column definitions for a table.
int	GetPrimaryKeys (const char *pszTable, const char *pszCatalog=nullptr, const char *pszSchema=nullptr)
	Fetch primary keys for a table.
int	GetTables (const char *pszCatalog=nullptr, const char *pszSchema=nullptr)
	Fetch tables in database.
void	DumpResult (FILE *fp, int bShowSchema=FALSE)
	Dump resultset to file.
int	CollectResultsInfo ()
	CollectResultsInfo.

Static Public Member Functions
static CPLString	GetTypeName (int)
	Get name for SQL column type.
static SQLSMALLINT	GetTypeMapping (SQLSMALLINT)
	Get appropriate C data type for SQL column type.

Detailed Description

Abstraction for statement, and resultset.

Includes methods for executing an SQL statement, and for accessing the resultset from that statement. Also provides for executing other ODBC requests that produce results sets such as SQLColumns() and SQLTables() requests.

Member Enumeration Documentation

Flag

enum CPLODBCStatement::Flag

Flags which control ODBC statement behavior.

Enumerator

RetrieveNumericColumnsAsDouble

Numeric column values should be retrieved as doubles, using either the SQL_C_DOUBLE or SQL_C_FLOAT types. By default numeric column values are retrieved as characters. Retrieving as character is the safest behavior, but can risk loss of precision. If set, GetColDataAsDouble should be used for numeric columns instead of GetColData. Warning: this flag can expose issues in particular ODBC drivers on different platforms. Use with caution.

Constructor & Destructor Documentation

CPLODBCStatement()

CPLODBCStatement::CPLODBCStatement ( CPLODBCSession *  poSession, int  flags = 0  )

explicit

Constructor.

The optional flags argument can be used to specify flags which control the behavior of the statement.

Member Function Documentation

Append() [1/4]

void CPLODBCStatement::Append

(

const char *

pszText

)

Append text to internal command.

The passed text is appended to the internal SQL command text.

Parameters

pszText

text to append.

Append() [2/4]

void CPLODBCStatement::Append

(

const std::string &

s

)

Append text to internal command.

The passed text is appended to the internal SQL command text.

Parameters

s	text to append.

Append() [3/4]

void CPLODBCStatement::Append

(

double

dfValue

)

Append to internal command.

The passed value is formatted and appended to the internal SQL command text.

Parameters

dfValue

value to append to the command.

Append() [4/4]

void CPLODBCStatement::Append

(

int

nValue

)

Append to internal command.

The passed value is formatted and appended to the internal SQL command text.

Parameters

nValue

value to append to the command.

AppendEscaped()

void CPLODBCStatement::AppendEscaped

(

const char *

pszText

)

Append text to internal command.

The passed text is appended to the internal SQL command text after escaping any special characters so it can be used as a character string in an SQL statement.

Parameters

pszText

text to append.

Appendf()

int CPLODBCStatement::Appendf	(	const char *	pszFormat,
			...
	)

Append to internal command.

The passed format is used to format other arguments and the result is appended to the internal command text. Long results may not be formatted properly, and should be appended with the direct Append() methods.

Parameters

pszFormat

printf() style format string.

Returns

FALSE if formatting fails due to result being too large.

DumpResult()

void CPLODBCStatement::DumpResult	(	FILE *	fp,
		int	bShowSchema = FALSE
	)

Dump resultset to file.

The contents of the current resultset are dumped in a simply formatted form to the provided file. If requested, the schema definition will be written first.

Parameters

fp	the file to write to. stdout or stderr are acceptable.
bShowSchema	TRUE to force writing schema information for the rowset before the rowset data itself. Default is FALSE.

ExecuteSQL()

int CPLODBCStatement::ExecuteSQL

(

const char *

pszStatement = nullptr

)

Execute an SQL statement.

This method will execute the passed (or stored) SQL statement, and initialize information about the resultset if there is one. If a NULL statement is passed, the internal stored statement that has been previously set via Append() or Appendf() calls will be used.

Parameters

pszStatement

the SQL statement to execute, or NULL if the internally saved one should be used.

Returns

TRUE on success or FALSE if there is an error. Error details can be fetched with OGRODBCSession::GetLastError().

Fetch()

int CPLODBCStatement::Fetch	(	int	nOrientation = SQL_FETCH_NEXT,
		int	nOffset = 0
	)

Fetch a new record.

Requests the next row in the current resultset using the SQLFetchScroll() call. Note that many ODBC drivers only support the default forward fetching one record at a time. Only SQL_FETCH_NEXT (the default) should be considered reliable on all drivers.

Currently it isn't clear how to determine whether an error or a normal out of data condition has occurred if Fetch() fails.

Parameters

nOrientation	One of SQL_FETCH_NEXT, SQL_FETCH_LAST, SQL_FETCH_PRIOR, SQL_FETCH_ABSOLUTE, or SQL_FETCH_RELATIVE (default is SQL_FETCH_NEXT).
nOffset	the offset (number of records), ignored for some orientations.

Returns

TRUE if a new row is successfully fetched, or FALSE if not.

GetColColumnDef()

const char * CPLODBCStatement::GetColColumnDef

(

int

iCol

)

Fetch a column default value.

Returns the default value of a column.

Parameters

iCol	the zero based column index.

Returns

NULL if the default value is not dpecified or the internal copy of the default value.

GetColCount()

int CPLODBCStatement::GetColCount

(

)

Fetch the resultset column count.

Returns

the column count, or zero if there is no resultset.

GetColData() [1/2]

const char * CPLODBCStatement::GetColData	(	const char *	pszColName,
		const char *	pszDefault = nullptr
	)

Fetch column data.

Fetches the data contents of the requested column for the currently loaded row. The result is returned as a string regardless of the column type. NULL is returned if an illegal column is given, or if the actual column is "NULL".

Parameters

pszColName	the name of the column requested.
pszDefault	the value to return if the column does not exist, or is NULL. Defaults to NULL.

Returns

pointer to internal column data or NULL on failure.

GetColData() [2/2]

const char * CPLODBCStatement::GetColData	(	int	iCol,
		const char *	pszDefault = nullptr
	)

Fetch column data.

Fetches the data contents of the requested column for the currently loaded row. The result is returned as a string regardless of the column type. NULL is returned if an illegal column is given, or if the actual column is "NULL".

Parameters

iCol	the zero based column to fetch.
pszDefault	the value to return if the column does not exist, or is NULL. Defaults to NULL.

Returns

pointer to internal column data or NULL on failure.

GetColDataAsDouble() [1/2]

double CPLODBCStatement::GetColDataAsDouble

(

const char *

pszColName

)

const

Fetch column data as a double value.

Fetches the data contents of the requested column for the currently loaded row as a double value.

Returns NaN if a non-numeric column is requested or the actual column value is "NULL".

Warning

this method can only be used if the Flag::RetrieveNumericColumnsAsDouble flag was set for the CPLODBCStatement.

Parameters

pszColName

the name of the column requested.

Returns

numeric column value or NaN on failure.

GetColDataAsDouble() [2/2]

double CPLODBCStatement::GetColDataAsDouble

(

int

iCol

)

const

Fetch column data as a double value.

Fetches the data contents of the requested column for the currently loaded row as a double value.

Returns NaN if a non-numeric column is requested or the actual column value is "NULL".

Warning

this method can only be used if the Flag::RetrieveNumericColumnsAsDouble flag was set for the CPLODBCStatement.

Parameters

iCol	the zero based column to fetch.

Returns

numeric column value or NaN on failure.

GetColId()

int CPLODBCStatement::GetColId

(

const char *

pszColName

)

const

Fetch column index.

Gets the column index corresponding with the passed name. The name comparisons are case insensitive.

Parameters

pszColName

the name to search for.

Returns

the column index, or -1 if not found.

GetColName()

const char * CPLODBCStatement::GetColName

(

int

iCol

)

Fetch a column name.

Parameters

iCol	the zero based column index.

Returns

NULL on failure (out of bounds column), or a pointer to an internal copy of the column name.

GetColNullable()

short CPLODBCStatement::GetColNullable

(

int

iCol

)

Fetch the column nullability.

Parameters

iCol	the zero based column index.

Returns

TRUE if the column may contains or FALSE otherwise.

GetColPrecision()

short CPLODBCStatement::GetColPrecision

(

int

iCol

)

Fetch the column precision.

Parameters

iCol	the zero based column index.

Returns

column precision, may be zero or the same as column size for columns to which it does not apply.

GetColSize()

short CPLODBCStatement::GetColSize

(

int

iCol

)

Fetch the column width.

Parameters

iCol	the zero based column index.

Returns

column width, zero for unknown width columns.

GetColType()

short CPLODBCStatement::GetColType

(

int

iCol

)

Fetch a column data type.

The return type code is a an ODBC SQL_ code, one of SQL_UNKNOWN_TYPE, SQL_CHAR, SQL_NUMERIC, SQL_DECIMAL, SQL_INTEGER, SQL_SMALLINT, SQL_FLOAT, SQL_REAL, SQL_DOUBLE, SQL_DATETIME, SQL_VARCHAR, SQL_TYPE_DATE, SQL_TYPE_TIME, SQL_TYPE_TIMESTAMPT.

Parameters

iCol	the zero based column index.

Returns

type code or -1 if the column is illegal.

GetColTypeName()

const char * CPLODBCStatement::GetColTypeName

(

int

iCol

)

Fetch a column data type name.

Returns data source-dependent data type name; for example, "CHAR", "VARCHAR", "MONEY", "LONG VARBINAR", or "CHAR ( ) FOR BIT DATA".

Parameters

iCol	the zero based column index.

Returns

NULL on failure (out of bounds column), or a pointer to an internal copy of the column dat type name.

GetColumns()

int CPLODBCStatement::GetColumns	(	const char *	pszTable,
		const char *	pszCatalog = nullptr,
		const char *	pszSchema = nullptr
	)

Fetch column definitions for a table.

The SQLColumn() method is used to fetch the definitions for the columns of a table (or other queryable object such as a view). The column definitions are digested and used to populate the CPLODBCStatement column definitions essentially as if a "SELECT * FROM tablename" had been done; however, no resultset will be available.

Parameters

pszTable	the name of the table to query information on. This should not be empty.
pszCatalog	the catalog to find the table in, use NULL (the default) if no catalog is available.
pszSchema	the schema to find the table in, use NULL (the default) if no schema is available.

Returns

TRUE on success or FALSE on failure.

GetPrimaryKeys()

int CPLODBCStatement::GetPrimaryKeys	(	const char *	pszTable,
		const char *	pszCatalog = nullptr,
		const char *	pszSchema = nullptr
	)

Fetch primary keys for a table.

The SQLPrimaryKeys() function is used to fetch a list of fields forming the primary key. The result is returned as a result set matching the SQLPrimaryKeys() function result set. The 4th column in the result set is the column name of the key, and if the result set contains only one record then that single field will be the complete primary key.

Parameters

pszTable	the name of the table to query information on. This should not be empty.
pszCatalog	the catalog to find the table in, use NULL (the default) if no catalog is available.
pszSchema	the schema to find the table in, use NULL (the default) if no schema is available.

Returns

TRUE on success or FALSE on failure.

GetTables()

int CPLODBCStatement::GetTables	(	const char *	pszCatalog = nullptr,
		const char *	pszSchema = nullptr
	)

Fetch tables in database.

The SQLTables() function is used to fetch a list tables in the database. The result is returned as a result set matching the SQLTables() function result set. The 3rd column in the result set is the table name. Only tables of type "TABLE" are returned.

Parameters

pszCatalog	the catalog to find the table in, use NULL (the default) if no catalog is available.
pszSchema	the schema to find the table in, use NULL (the default) if no schema is available.

Returns

TRUE on success or FALSE on failure.

GetTypeMapping()

SQLSMALLINT CPLODBCStatement::GetTypeMapping ( SQLSMALLINT  nTypeCode )

static

Get appropriate C data type for SQL column type.

Returns a C data type code, corresponding to the indicated SQL data type code (as returned from CPLODBCStatement::GetColType()).

Parameters

nTypeCode

the SQL_ code, such as SQL_CHAR.

Returns

data type code. The valid code is always returned. If SQL code is not recognised, SQL_C_BINARY will be returned.

GetTypeName()

CPLString CPLODBCStatement::GetTypeName ( int  nTypeCode )

static

Get name for SQL column type.

Returns a string name for the indicated type code (as returned from CPLODBCStatement::GetColType()).

Parameters

nTypeCode

the SQL_ code, such as SQL_CHAR.

Returns

internal string, "UNKNOWN" if code not recognised.

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The documentation for this class was generated from the following files:

• cpl_odbc.h
• cpl_odbc.cpp