mysql协议学习(三)--OK报文

来源：互联网发布：php微信订餐系统源码编辑：程序博客网时间：2024/05/16 06:46

Payload of OK Packet

TypeNameDescriptionint<1>header[00] or [fe] the OK packet headerint<lenenc>affected_rowsaffected rowsint<lenenc>last_insert_idlast insert-idif capabilities & CLIENT_PROTOCOL_41 { int<2>status_flagsStatus Flags int<2>warningsnumber of warnings} elseif capabilities & CLIENT_TRANSACTIONS { int<2>status_flagsStatus Flags}if capabilities & CLIENT_SESSION_TRACK { string<lenenc>infohuman readable status information if status_flags & SERVER_SESSION_STATE_CHANGED { string<lenenc>session_state_changessession state info }} else { string<EOF>infohuman readable status information}

对于执行成功的命令，通常会返回OK报文

OK报文和EOF报文的区别

对于OK报文和EOF报文，其header字段都可能为0xfe，那么有如下规则来区分这两种报文

OK Packet：length of packet > 7

EOF Packet：length of packet < 9

eg：

OK with CLIENT_PROTOCOL_41. 0 affected rows, last-insert-id was 0, AUTOCOMMIT enabled, 0 warnings. No further info.

07 00 00 0200000002    0000 00

...........

Status Flags说明：

FlagValueCommentSERVER_STATUS_IN_TRANS0x0001a transaction is activeSERVER_STATUS_AUTOCOMMIT0x0002auto-commit is enabledSERVER_MORE_RESULTS_EXISTS0x0008

SERVER_STATUS_NO_GOOD_INDEX_USED0x0010

SERVER_STATUS_NO_INDEX_USED0x0020

SERVER_STATUS_CURSOR_EXISTS0x0040Used by Binary Protocol Resultset to signal thatCOM_STMT_FETCH must be used to fetch the row-data.SERVER_STATUS_LAST_ROW_SENT0x0080

SERVER_STATUS_DB_DROPPED0x0100

SERVER_STATUS_NO_BACKSLASH_ESCAPES0x0200

SERVER_STATUS_METADATA_CHANGED0x0400

SERVER_QUERY_WAS_SLOW0x0800

SERVER_PS_OUT_PARAMS0x1000

SERVER_STATUS_IN_TRANS_READONLY0x2000in a read-only transactionSERVER_SESSION_STATE_CHANGED0x4000connection state information has changed

Session State Information

该部分信息由以下部分组成：

TypeNameDescriptionint<1>typetype of datastring<lenenc>datadata of the changed session info

其中type有3种，分别是：

types of State Change Information

NameValueDescriptionSESSION_TRACK_SYSTEM_VARIABLES0x00one or more system variables changed. See also:session_track_system_variablesSESSION_TRACK_SCHEMA0x01schema changed. See also: session_track_schemaSESSION_TRACK_STATE_CHANGE0x02"track state change" changed. See also:session_track_state_change
不同type类型对应的data组成是不同的

SESSION_TRACK_SYSTEM_VARIABLES 对应的data字段内容

TypeNameDescriptionstring<lenenc>namename of the changed system variablestring<lenenc>valuevalue of the changed system variable

eg：

SET autocommit = OFF

00 0f 0a 61 75 74 6f 63   6f 6d 6d 69 7403 4f 4646

....autocommit.OFF

第1个字节00表示type=SESSION_TRACK_SYSTEM_VARIABLES，接下来的部分组成为data字段，类型是string<lenenc>，其中第1个字节0f表示接下来的字符串长度为15个字节（0x0f = 15），而SESSION_TRACK_SYSTEM_VARIABLES的data字段又分为两个字段 name（string<lenenc>）和 value（string<lenenc>），那么接下来的 0a 61 75 74 6f 63 6f 6d 6d 69 74 （len = 0x0a）和 03 4f 46 46 （len = 0x03）则分别为name字段和value字段的内容。

SESSION_TRACK_SCHEMA 对应的data字段内容

TypeNameDescriptionstring<lenenc>namename of the changed schema

eg：

USE test

01 05 04 74 65 73 74

...test

第1个字节01表示type=SESSION_TRACK_SCHEMA，接下来的部分组成为data字段，类型是string<lenenc>，其中第1个字节05表示接下来的字符串长度为5个字节，data字段内容为 04 74 65 73 74（len = 0x04）

SESSION_TRACK_STATE_CHANGE 对应的data字段内容

备注：A flag byte that indicates whether session state changes occurred. This flag is represented as an ASCII value

TypeNameDescriptionstring<lenenc>is_tracked[31] ("1") if state tracking got enabled.

0 0