MySQL  8.0.19
Source Code Documentation
COM_STMT_PREPARE

Creates a prepared statement for the passed query string.

The server returns a COM_STMT_PREPARE Response which contains a statement-id which is ised to identify the prepared statement.

Payload
TypeNameDescription
int<1> command 0x16: COM_STMT_PREPARE
string<EOF> query The query to prepare
Example
1c 00 00 00 16 53 45 4c 45 43 54 20 43 4f 4e 43 .....SELECT CONC
41 54 28 3f 2c 20 3f 29 20 41 53 20 63 6f 6c 31 AT(?, ?) AS col1
Returns
COM_STMT_PREPARE_OK on success, ERR_Packet otherwise
See also
mysqld_stmt_prepare, mysql_stmt_precheck, Prepared_statement, mysql_stmt_prepare, mysql_stmt_init
Note
As LOAD DATA isn't supported by COM_STMT_PREPARE yet, no LOCAL INFILE Request is expected here. This is unlike COM_QUERY Response.

COM_STMT_PREPARE Response

If COM_STMT_PREPARE succeeded, it sends a COM_STMT_PREPARE_OK

COM_STMT_PREPARE_OK

Payload of the first packet
TypeNameDescription
int<1> status 0x00: OK: Ignored by cli_read_prepare_result
int<4> statement_id statement ID
int<2> num_columns Number of columns
int<2> num_params Number of parameters
int<1> reserved_1 [00] filler
if (packet_lenght > 12) {
int<2> warning_count Number of warnings
if capabilities & CLIENT_OPTIONAL_RESULTSET_METADATA {
int<1> metadata_follows Flag specifying if metadata are skipped or not. See enum_resultset_metadata
} – CLIENT_OPTIONAL_RESULTSET_METADATA {
} – packet_lenght > 12

if num_params > 0 and CLIENT_OPTIONAL_RESULTSET_METADATA is not set or if medatdata_follows is RESULTSET_METADATA_FULL num_params packets will follow. Then a EOF_Packet will be transmitted, provided that CLIENT_DEPRECATE_EOF is not set.

Parameter definition block
TypeNameDescription
num_params * Column Definition
if (not capabilities & CLIENT_DEPRECATE_EOF) {
EOF_Packet
} –CLIENT_DEPRECATE_EOF

if num_columns > 0 and CLIENT_OPTIONAL_RESULTSET_METADATA is not set or if medatdata_follows is RESULTSET_METADATA_FULL num_columns packets will follow. Then a EOF_Packet will be transmitted, provided that CLIENT_DEPRECATE_EOF is not set.

Column definition block
TypeNameDescription
num_columns * Column Definition
if (not capabilities & CLIENT_DEPRECATE_EOF) {
EOF_Packet
} –CLIENT_DEPRECATE_EOF
Example
for a prepared query like SELECT CONCAT(?, ?) AS col1 and no CLIENT_OPTIONAL_RESULTSET_METADATA
0c 00 00 01 00 01 00 00 00 01 00 02 00 00 00 00| ................
17 00 00 02 03 64 65 66 00 00 00 01 3f 00 0c 3f .....def....?..?
00 00 00 00 00 fd 80 00 00 00 00|17 00 00 03 03 ................
64 65 66 00 00 00 01 3f 00 0c 3f 00 00 00 00 00 def....?..?.....
fd 80 00 00 00 00|05 00 00 04 fe 00 00 02 00|1a ................
00 00 05 03 64 65 66 00 00 00 04 63 6f 6c 31 00 ....def....col1.
0c 3f 00 00 00 00 00 fd 80 00 1f 00 00|05 00 00 .?..............
06 fe 00 00 02 00 ...
Example
for a a query without parameters and resultset like DO 1 and no CLIENT_OPTIONAL_RESULTSET_METADATA :
0c 00 00 01 00 01 00 00 00 00 00 00 00 00 00 00
See also
cli_read_prepare_result, mysql_stmt_prepare, send_statement, THD::send_result_metadata