# pqxx Namespace Reference

The home of all libpqxx classes, functions, templates, etc. More...

## Classes

class | basic_connection
| The ultimate template that defines a connection type. More...
class | binarystring
class | cachedresult
class | connect_direct
| Connection policy; creates an immediate connection to a database. More...
class | connect_lazy
| Lazy connection policy; causes connection to be deferred until first use. More...
class | connect_async
| Asynchronous connection policy; connects "in the background". More...
class | connect_null
| Nonfunctional, always-down connection policy for debugging purposes. More...
struct | noticer
| Base class for user-definable error/warning message processor. More...
struct | nonnoticer
| No-op message noticer; produces no output. More...
class | connection_base
| connection_base abstract base class; represents a connection to a database. More...
class | scoped_noticer
| Temporarily set different noticer for connection, then restore old one. More...
class | disable_noticer
| Temporarily disable the notice processor. More...
class | connectionpolicy
class | Cursor
| SQL cursor class. More...
class | cursor_base
| Common definitions for cursor types. More...
class | basic_cursor
| The simplest form of cursor, with no concept of position or stride. More...
class | absolute_cursor
| Cursor that knows its position. More...
class | icursorstream
| Simple read-only cursor represented as a stream of results. More...
class | icursor_iterator
| Approximate istream_iterator for icursorstream. More...
class | dbtransaction
class | broken_connection
| Exception class for lost or failed backend connection. More...
class | sql_error
| Exception class for failed queries. More...
class | in_doubt_error
| "Help, I don't know whether transaction was committed successfully!" More...
class | internal_error
| Internal error in libpqxx library. More...
class | feature_not_supported
| Database feature not supported in current setup. More...
class | data_exception
| Error in data provided to SQL statement. More...
class | integrity_constraint_violation
class | invalid_cursor_state
class | invalid_sql_statement_name
class | invalid_cursor_name
class | syntax_error
class | undefined_column
class | undefined_function
class | undefined_table
class | insufficient_privilege
class | insufficient_resources
| Resource shortage on the server. More...
class | disk_full
class | out_of_memory
class | too_many_connections
struct | isolation_traits
| Traits class to describe an isolation level; primarly for libpqxx's own use. More...
class | largeobject
| Identity of a large object. More...
class | largeobjectaccess
| Accessor for large object's contents. More...
class | largeobject_streambuf
| Streambuf to use large objects in standard I/O streams. More...
class | basic_ilostream
| Input stream that gets its data from a large object. More...
class | basic_olostream
| Output stream that writes data back to a large object. More...
class | basic_lostream
| Stream that reads and writes a large object. More...
class | nontransaction
class | pipeline
| Processes several queries in FIFO manner, optimized for high throughput. More...
class | result
| Query or command result set. More...
class | field_streambuf
class | basic_fieldstream
| Input stream that gets its data from a result field. More...
class | basic_robusttransaction
class | robusttransaction
| Slightly slower, better-fortified version of transaction. More...
class | subtransaction
| "Transaction" nested within another transaction More...
class | tablereader
| Efficiently pull data directly out of a table. More...
class | tablestream
| Base class for streaming data to/from database tables. More...
class | tablewriter
| Efficiently write data directly to a database table. More...
class | basic_transaction
class | transaction
| Standard back-end transaction, templatized on isolation level. More...
class | transaction_base
class | transactor
class | trigger
class | items
| Container of items with easy contents initialization and string rendering. More...

## Namespaces

namespace | internal
| Private namespace for libpqxx's internal use; do not access.

namespace | prepare
| Dedicated namespace for helper types related to prepared statements.

## Typedefs

typedef cachedresult | CachedResult
typedef basic_connection< connect_direct > | connection
| The "standard" connection type: connect to database right now.
typedef basic_connection< connect_lazy > | lazyconnection
| A "lazy" connection type: connect to database only when needed.
typedef basic_connection< connect_async > | asyncconnection
| "Asynchronous" connection type: start connecting, but don't wait for it
typedef basic_connection< connect_null > | nullconnection
| A "dummy" connection type: don't connect to any database at all.
typedef basic_cursor< cursor_base::random_access, cursor_base::read_only > | cursor
| Convenience typedef: the most common cursor type (read-only, random access).
typedef absolute_cursor< cursor_base::random_access, cursor_base::read_only > | abscursor
| Convenience typedef: read-only, random-access absolutely-positioning cursor.
typedef basic_ilostream< char > | ilostream
typedef basic_olostream< char > | olostream
typedef basic_lostream< char > | lostream
typedef unsigned int | oid
| PostgreSQL database row identifier.
typedef nontransaction | NonTransaction
typedef binarystring | BinaryString
typedef result | Result
typedef basic_fieldstream< char > | fieldstream
typedef robusttransaction< read_committed > | RobustTransaction
typedef transaction | work
| Bog-standard, default transaction type.

## Enumerations

enum | isolation_level { read_committed, serializable }
| Transaction isolation levels; PostgreSQL doesn't implement all SQL levels. More...

## Functions

PGSTD::string PQXX_LIBEXPORT | escape_binary (const PGSTD::string &bin)
| Escape binary string for inclusion in SQL.
PGSTD::string PQXX_LIBEXPORT | escape_binary (const char bin[])
| Escape binary string for inclusion in SQL.
PGSTD::string PQXX_LIBEXPORT | escape_binary (const char bin[], size_t len)
| Escape binary string for inclusion in SQL.
PGSTD::string PQXX_LIBEXPORT | escape_binary (const unsigned char bin[])
| Escape binary string for inclusion in SQL.
PGSTD::string PQXX_LIBEXPORT | escape_binary (const unsigned char bin[], size_t len)
| Escape binary string for inclusion in SQL.
PGSTD::string | encrypt_password (const PGSTD::string &user, const PGSTD::string &password)
| Encrypt password for given user. Requires libpq 8.2 or better.
template<>
void | cursor_base::check_displacement< cursor_base::forward_only > (difference_type) const
template<typename STREAM>
STREAM & | operator<< (STREAM &S, const pqxx::result::field &F)
| Write a result field to any type of stream.
template<typename T>
void | from_string (const result::field &F, T &Obj)
| Convert a field's string contents to another type.
template<>
PGSTD::string | to_string (const result::field &Obj)
| Convert a field to a string.
template<>
bool | result::field::to< PGSTD::string > (PGSTD::string &Obj) const
| Specialization: `to(string &)`.
result::const_iterator | operator+ (result::const_iterator::difference_type o, result::const_iterator i)
result::const_reverse_iterator | operator+ (result::const_reverse_iterator::difference_type n, const result::const_reverse_iterator &i)
result::const_fielditerator | operator+ (result::const_fielditerator::difference_type o, result::const_fielditerator i)
template<typename T>
void | error_unsupported_type_in_string_conversion (T)
| Dummy name, used by libpqxx in deliberate link errors.
template<typename T>
PGSTD::string | error_ambiguous_string_conversion (T)
| Dummy name, used to generate meaningful link errors.
template<typename T>
void | from_string (const char Str[], T &Obj)
| Attempt to convert postgres-generated string to given built-in type.
template<typename T>
void | from_string (const char Str[], T &Obj, size_t)
| Conversion with known string length (for strings that may contain nuls).
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], PGSTD::string &, size_t)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], long &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], unsigned long &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], int &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], unsigned int &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], short &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], unsigned short &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], float &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], double &)
template<>
void PQXX_LIBEXPORT | from_string (const char Str[], bool &)
template<>
void | from_string (const char Str[], PGSTD::string &Obj)
template<>
void | from_string (const char Str[], PGSTD::stringstream &Obj)
template<typename T>
void | from_string (const PGSTD::string &Str, T &Obj)
template<typename T>
void | from_string (const PGSTD::stringstream &Str, T &Obj)
template<>
void | from_string (const PGSTD::string &Str, PGSTD::string &Obj)
template<>
void | from_string (const char[], char &Obj)
template<>
void | from_string (const char[], signed char &Obj)
template<>
void | from_string (const char[], unsigned char &Obj)
template<>
void | from_string (const PGSTD::string &, char &Obj)
template<>
void | from_string (const PGSTD::string &, signed char &Obj)
template<>
void | from_string (const PGSTD::string &, unsigned char &Obj)
template<typename T>
PGSTD::string | to_string (const T &)
| Convert built-in type to a readable string that PostgreSQL will understand.
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const short &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const unsigned short &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const int &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const unsigned int &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const long &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const unsigned long &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const float &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const double &)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const bool &)
PGSTD::string | to_string (const char Obj[])
PGSTD::string | to_string (const PGSTD::stringstream &Obj)
PGSTD::string | to_string (const PGSTD::string &Obj)
template<>
PGSTD::string PQXX_LIBEXPORT | to_string (const char &)
template<>
PGSTD::string | to_string (const signed char &Obj)
template<>
PGSTD::string | to_string (const unsigned char &Obj)
template<typename ITER, typename ACCESS>
PGSTD::string | separated_list (const PGSTD::string &sep, ITER begin, ITER end, ACCESS access)
| Access iterators using ACCESS functor, returning separator-separated list.
template<typename ITER>
PGSTD::string | separated_list (const PGSTD::string &sep, ITER begin, ITER end)
| Render sequence as a string, using given separator between items.
template<typename OBJ>
PGSTD::string | separated_list (const PGSTD::string &sep, OBJ *begin, OBJ *end)
| Render array as a string, using given separator between items.
template<typename CONTAINER>
PGSTD::string | separated_list (const PGSTD::string &sep, const CONTAINER &c)
| Render items in a container as a string, using given separator.
PGSTD::string PQXX_LIBEXPORT | sqlesc (const char str[]) PQXX_DEPRECATED
| Escape nul-terminated string for inclusion in SQL strings.
PGSTD::string PQXX_LIBEXPORT | sqlesc (const char str[], size_t maxlen) PQXX_DEPRECATED
| Escape string for inclusion in SQL strings.
PGSTD::string PQXX_LIBEXPORT | sqlesc (const PGSTD::string &) PQXX_DEPRECATED
| Escape string for inclusion in SQL strings.
string | escape_binary (const unsigned char bin[], size_t len)
| Escape binary string for inclusion in SQL.
string | escape_binary (const unsigned char bin[])
| Escape binary string for inclusion in SQL.
string | escape_binary (const char bin[], size_t len)
| Escape binary string for inclusion in SQL.
string | escape_binary (const char bin[])
| Escape binary string for inclusion in SQL.
string | escape_binary (const string &bin)
string | sqlesc (const char str[])
| Escape nul-terminated string for inclusion in SQL strings.
string | sqlesc (const char str[], size_t maxlen)
| Escape string for inclusion in SQL strings.
string | sqlesc (const string &str)

## Variables

const oid | oid_none = 0
| The "null" oid.

## Detailed Description

The home of all libpqxx classes, functions, templates, etc.

## Typedef Documentation

typedef absolute_cursor<cursor_base::random_access, cursor_base::read_only> pqxx::abscursor

Convenience typedef: read-only, random-access absolutely-positioning cursor.

typedef binarystring pqxx::BinaryString

Deprecated:
  For compatibility with old BinaryString class

typedef cachedresult pqxx::CachedResult

Deprecated:
  For compatibility with the old CachedResult class

typedef basic_cursor<cursor_base::random_access, cursor_base::read_only> pqxx::cursor

Convenience typedef: the most common cursor type (read-only, random access).

typedef basic_fieldstream<char> pqxx::fieldstream

typedef basic_ilostream<char> pqxx::ilostream

typedef basic_lostream<char> pqxx::lostream

typedef nontransaction pqxx::NonTransaction

Deprecated:
  For compatibility with the old NonTransaction class

typedef unsigned int pqxx::oid

PostgreSQL database row identifier.

typedef basic_olostream<char> pqxx::olostream

typedef result pqxx::Result

Deprecated:
  For compatibility with old Result class

typedef robusttransaction<read_committed> pqxx::RobustTransaction

Deprecated:
  For compatibility with old RobustTransaction class

## Enumeration Type Documentation

enum pqxx::isolation_level

Transaction isolation levels; PostgreSQL doesn't implement all SQL levels.

The only levels implemented in postgres are read_committed and serializable; SQL also defines read_uncommitted and repeatable_read. Unless you're bent on using nasty tricks to communicate between ongoing transactions and such, you won't really need isolation levels for anything except performance optimization. In that case, you can safely emulate read_uncommitted by using read_committed and repeatable_read by using serializable. In general, serializable is the safest choice.

Enumerator:

  read_committed |
  serializable |

## Function Documentation

template<>

void pqxx::cursor_base::check_displacement< cursor_base::forward_only > | ( | difference_type |  | ) | const

PGSTD::string pqxx::encrypt_password | ( | const PGSTD::string & | user,
|  | const PGSTD::string & | password |
| ) |  |  |

Encrypt password for given user. Requires libpq 8.2 or better.

Use this when setting a new password for the user if password encryption is enabled. Inputs are the username the password is for, and the plaintext password.

Returns:
  encrypted version of the password, suitable for encrypted PostgreSQL authentication.

Thus the password for a user can be changed with:

     void setpw(transaction_base &t, const string &user, const string &pw)
     {
       t.exec("ALTER USER " + user + " "
            "PASSWORD '" + encrypt_password(user,pw) + "'");
     }

Since:
  libpq 8.2

string pqxx::escape_binary | ( | const string & | bin | ) |

template<typename T>

void pqxx::from_string | ( | const result::field & | F,
|  | T & | Obj |
| ) |  |  |

Convert a field's string contents to another type.

result::const_fielditerator pqxx::operator+ | ( | result::const_fielditerator::difference_type | o,
|  | result::const_fielditerator | i |
| ) |  |  |

result::const_reverse_iterator pqxx::operator+ | ( | result::const_reverse_iterator::difference_type | n,
|  | const result::const_reverse_iterator & | i |
| ) |  |  |

result::const_iterator pqxx::operator+ | ( | result::const_iterator::difference_type | o,
|  | result::const_iterator | i |
| ) |  |  |

template<typename STREAM>

STREAM& pqxx::operator<< | ( | STREAM & | S,
|  | const pqxx::result::field & | F |
| ) |  |  |

Write a result field to any type of stream.

This can be convenient when writing a field to an output stream. More importantly, it lets you write a field to e.g. a `stringstream` which you can then use to read, format and convert the field in ways that to() does not support.

Example: parse a field into a variable of the nonstandard "<tt>long long</tt>" type.

     extern result R;
     long long L;
     stringstream S;

     // Write field's string into S
     S << R[0][0];

     // Parse contents of S into L
     S >> L;

template<>

bool pqxx::result::field::to< PGSTD::string > | ( | PGSTD::string & | Obj | ) | const

Specialization: `to(string &)`.

template<typename ITER, typename ACCESS>

PGSTD::string pqxx::separated_list | ( | const PGSTD::string & | sep,
|  | ITER | begin,
|  | ITER | end,
|  | ACCESS | access |
| ) |  |  |

Access iterators using ACCESS functor, returning separator-separated list.

Parameters:

  | sep | separator string (to be placed between items)
  | begin | beginning of items sequence
  | end | end of items sequence
  | access | functor defining how to dereference sequence elements

string pqxx::sqlesc | ( | const string & | str | ) |

template<>

PGSTD::string pqxx::to_string | ( | const result::field & | Obj | ) |

Convert a field to a string.

## Variable Documentation

const oid pqxx::oid_none = 0

The "null" oid.