COM_STMT_EXECUTE

Executes a previously prepared statement.

If specific data is large, it can be sent separately prior to this command (see COM_STMT_SEND_LONG_DATA).

If a statement is re-executed without changing the bind types, the types do not need to be sent to the server again.

Direction

Client to server.

Fields

Statement Id

Statement id is the identifier of the prepared statement (from COM_STMT_PREPARE answer)

Specific "-1" statement id value

Since MariaDB server version 10.2, value -1 (0xFFFFFFFF) can be used to indicate to use the last statement prepared on current connection if no COM_STMT_PREPARE has fail since.

This permit pipelining :

  • send COM_STMT_PREPARE + COM_STMT_EXECUTE with statement id -1
  • read COM_STMT_PREPARE + COM_STMT_EXECUTE response

In case COM_STMT_PREPARE returns an error, COM_STMT_EXECUTE will return an error that statement id -1 is unknown. This permits to avoid much of the network latency.

Flag

0no cursor
1read only
2cursor for update
4scrollable cursor

Parameter flag

parameter type flag byte:

128unsigned

NULL-Bitmap

The NULL-Bitmap indicates if parameters are null (one bit per parameter).
NULL-bitmap size is (parameter number + 7) / 8

Binary parameter encoding

COM_STMT_EXECUTE response

The server can answer with 3 different responses:

  • 0xff: ERR_Packet if any errors occur.
  • 0x00: OK_packet when query execution works without resultset.
  • one (or more) Resultset, when query execution return rows (in case of SELECT query for example).

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