Exec
sends a command to the backend server. It's probably more desirable to
use one of the next two functions.
ExecStatusType PgConnection::Exec(const char* query)
Returns the result status of the command. The following status results can be expected:
PGRES_EMPTY_QUERY |
PGRES_COMMAND_OK, if the command was not a query |
PGRES_TUPLES_OK, if the query successfully returned tuples |
PGRES_COPY_OUT |
PGRES_COPY_IN |
PGRES_BAD_RESPONSE, if an unexpected response was received |
PGRES_NONFATAL_ERROR |
PGRES_FATAL_ERROR |
ExecCommandOk
sends a non-query command
(one that does not return rows) to the backend server.
int PgConnection::ExecCommandOk(const char *query)
Returns true (1) if the command succeeds.
ExecTuplesOk
Sends a query command (one that returns rows) to the backend server.
int PgConnection::ExecTuplesOk(const char *query)
Returns true (1) if the query succeeds.
ErrorMessage
returns the last error message text.
const char *PgConnection::ErrorMessage()
Tuples
returns the number of tuples (rows) in the query result.
int PgDatabase::Tuples() const
Fields
returns the number of fields (rows) in each tuple of the query result.
int PgDatabase::Fields()
FieldName
returns the field (column) name associated with the given field index.
Field indices start at 0.
const char *PgDatabase::FieldName(int field_num) const
FieldNum
returns the field (column) index associated with
the given field name.
int PgDatabase::FieldNum(const char* field_name) const
-1 is returned if the given name does not match any field.
FieldType
returns the field type associated with the given field index. The
integer returned is an internal coding of the type. Field indices
start at 0.
Oid PgDatabase::FieldType(int field_num) const
FieldType
returns the field type associated with the given field name. The
integer returned is an internal coding of the type. Field indices
start at 0.
Oid PgDatabase::FieldType(const char* field_name) const
FieldSize
returns the size in bytes of the field associated with the given
field index. Field indices start at 0.
int PgDatabase::FieldSize(int field_num) const
Returns the space allocated for this field in a database tuple given the field number. In other words the size of the server's binary representation of the data type. -1 is returned if the field is variable size.
FieldSize
returns the size in bytes of the field associated with the given
field index. Field indices start at 0.
int PgDatabase::FieldSize(const char *field_name) const
Returns the space allocated for this field in a database tuple given the field name. In other words the size of the server's binary representation of the data type. -1 is returned if the field is variable size.
GetValue
returns a single field (column)
value of one tuple of a PGresult.
Tuple and field indices start at 0.
const char *PgDatabase::GetValue(int tup_num, int field_num) const
For most queries, the value returned by
GetValue
is a null-terminated string
representation of the attribute value. But if
BinaryTuples
is true, the value returned by
GetValue
is the binary representation of
the type in the internal format of the backend server (but not
including the size word, if the field is variable-length). It is
then the programmer's responsibility to cast and convert the
data to the correct C type. The pointer returned by
GetValue
points to storage that is part of
the PGresult structure. One should not
modify it, and one must explicitly copy the value into other
storage if it is to be used past the lifetime of the
PGresult structure itself.
BinaryTuples
is not yet implemented.
GetValue
returns a single field (column)
value of one tuple of a PGresult.
Tuple and field indices start at 0.
const char *PgDatabase::GetValue(int tup_num, const char *field_name) const
For most queries, the value returned by
GetValue
is a null-terminated string
representation of the attribute value. But if
BinaryTuples
is true, the value returned by
GetValue
is the binary representation of
the type in the internal format of the backend server (but not
including the size word, if the field is variable-length). It is
then the programmer's responsibility to cast and convert the
data to the correct C type. The pointer returned by
GetValue
points to storage that is part of
the PGresult structure. One should not
modify it, and one must explicitly copy the value into other
storage if it is to be used past the lifetime of the
PGresult structure itself.
BinaryTuples
is not yet implemented.
GetLength
returns the length of a field
(column) in bytes. Tuple and field indices start at 0.
int PgDatabase::GetLength(int tup_num, int field_num) const
This is the actual data length for the particular data value,
that is the size of the object pointed to by
GetValue
. Note that for
character-represented values, this size has little to do with
the binary size reported by PQfsize
.
GetLength
returns the length of a field
(column) in bytes. Tuple and field indices start at 0.
int PgDatabase::GetLength(int tup_num, const char* field_name) const
This is the actual data length for the particular data value,
that is the size of the object pointed to by
GetValue
. Note that for
character-represented values, this size has little to do with
the binary size reported by PQfsize
.
GetIsNull
returns whether a field has the null value.
bool GetIsNull(int tup_num, int field_num) const
Note that GetValue
will return the empty
string for null fields, not the NULL pointer.
GetIsNull
returns whether a field has the
null value.
bool GetIsNull(int tup_num, const char *field_name) const
Note that GetValue
will return the empty
string for null fields, not the NULL pointer.
DisplayTuples
prints out all the tuples
and, optionally, the attribute names to the specified output
stream.
void PgDatabase::DisplayTuples(FILE *out = 0, bool fillAlign = true, const char* fieldSep = "|", bool printHeader = true, bool quiet = false) const
This function is obsolescent.
PrintTuples
prints out all the tuples and,
optionally, the attribute names to the specified output stream.
void PgDatabase::PrintTuples(FILE *out = 0, bool printAttName = true, bool terseOutput = false, bool fillAlign = false) const
This function is obsolescent.
CmdTuples
returns the number of rows
affected after an INSERT,
UPDATE, or DELETE. If the
command was anything else, it returns -1.
int PgDatabase::CmdTuples() const
OidStatus
const char *PgDatabase::OidStatus() const