libpqxx
The C++ client library for PostgreSQL
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Cursor with SQL positioning semantics. More...
Public Member Functions | |
sql_cursor (transaction_base &t, std::string_view query, std::string_view cname, cursor_base::access_policy ap, cursor_base::update_policy up, cursor_base::ownership_policy op, bool hold) | |
sql_cursor (transaction_base &t, std::string_view cname, cursor_base::ownership_policy op) | |
result | fetch (difference_type rows, difference_type &displacement) |
result | fetch (difference_type rows) |
difference_type | move (difference_type rows, difference_type &displacement) |
difference_type | move (difference_type rows) |
difference_type | pos () const noexcept |
Current position, or -1 for unknown. | |
difference_type | endpos () const noexcept |
End position, or -1 for unknown. | |
result const & | empty_result () const noexcept |
Return zero-row result for this cursor. | |
void | close () noexcept |
Cursor with SQL positioning semantics.
Thin wrapper around an SQL cursor, with SQL's ideas of positioning.
SQL cursors have pre-increment/pre-decrement semantics, with on either end of the result set a special position that does not repesent a row. This class models SQL cursors for the purpose of implementing more C++-like semantics on top.
Positions of actual rows are numbered starting at 1. Position 0 exists but does not refer to a row. There is a similar non-row position at the end of the result set.
Don't use this at home. You deserve better. Use the stateless_cursor instead.
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inlinenoexcept |
End position, or -1 for unknown.
Returns the final position, just after the last row in the result set. The starting position, just before the first row, counts as position zero.
End position is unknown until it is encountered during use.
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inlinenoexcept |
Current position, or -1 for unknown.
The starting position, just before the first row, counts as position zero.
Position may be unknown if (and only if) this cursor was adopted, and has never hit its starting position (position zero).