mysql/mysql_client.md

local mysql = require'mysql_client'

MySQL client protocol

Status

This library is considered production ready.

Example

local mysql = require "resty.mysql"
local db, err = mysql:new()
if not db then
  ngx.say("failed to instantiate mysql: ", err)
  return
end

db:set_timeout(1000) -- 1 sec

-- or connect to a unix domain socket file listened
-- by a mysql server:
--     local ok, err, errcode, sqlstate =
--           db:connect{
--              path = "/path/to/mysql.sock",
--              database = "ngx_test",
--              user = "ngx_test",
--              password = "ngx_test" }

local ok, err, errcode, sqlstate = db:connect{
  host = "127.0.0.1",
  port = 3306,
  database = "ngx_test",
  user = "ngx_test",
  password = "ngx_test",
  charset = "utf8",
  max_packet_size = 1024 * 1024,
}

if not ok then
  ngx.say("failed to connect: ", err, ": ", errcode, " ", sqlstate)
  return
end

ngx.say("connected to mysql.")

local res, err, errcode, sqlstate =
  db:query("drop table if exists cats")
if not res then
  ngx.say("bad result: ", err, ": ", errcode, ": ", sqlstate, ".")
  return
end

res, err, errcode, sqlstate =
  db:query("create table cats "
			  .. "(id serial primary key, "
			  .. "name varchar(5))")
if not res then
  ngx.say("bad result: ", err, ": ", errcode, ": ", sqlstate, ".")
  return
end

ngx.say("table cats created.")

res, err, errcode, sqlstate =
  db:query("insert into cats (name) "
			  .. "values (\'Bob\'),(\'\'),(null)")
if not res then
  ngx.say("bad result: ", err, ": ", errcode, ": ", sqlstate, ".")
  return
end

ngx.say(res.affected_rows, " rows inserted into table cats ",
		"(last insert id: ", res.insert_id, ")")

-- run a select query, expected about 10 rows in
-- the result set:
res, err, errcode, sqlstate =
  db:query("select * from cats order by id asc", 10)
if not res then
  ngx.say("bad result: ", err, ": ", errcode, ": ", sqlstate, ".")
  return
end

local cjson = require "cjson"
ngx.say("result: ", cjson.encode(res))

-- put it into the connection pool of size 100,
-- with 10 seconds max idle timeout
local ok, err = db:set_keepalive(10000, 100)
if not ok then
  ngx.say("failed to set keepalive: ", err)
  return
end

-- or just close the connection right away:
-- local ok, err = db:close()
-- if not ok then
--     ngx.say("failed to close: ", err)
--     return
-- end

API

mysql:new() -> db | nil,err

Creates a MySQL connection object.

db:connect(options) -> ok | nil,err,errcode,sqlstate

Connect to a MySQL server.

The options argument is a Lua table holding the following keys:

• host: the host name for the MySQL server.
• port: the port that the MySQL server is listening on. Default to 3306.
• path: the path of the unix socket file listened by the MySQL server.
• database: the MySQL database name.
• user: MySQL account name for login.
• password: MySQL account password for login (in clear text).
• charset: the character set used for the connection, which can be one of: big5, dec8, cp850, hp8, koi8r, latin1, latin2, swe7, ascii, ujis, sjis, hebrew, tis620, euckr, koi8u, gb2312, greek, cp1250, gbk, latin5, armscii8, utf8, ucs2, cp866, keybcs2, macce, macroman, cp852, latin7, utf8mb4, cp1251, utf16, utf16le, cp1256, cp1257, utf32, binary, geostd8, cp932, eucjpms, gb18030.
• max_packet_size: the upper limit for the reply packets sent from the server (default to 1MB).
• ssl: if true, then uses SSL to connect to MySQL (default to false). If the server does not have SSL support (or just disabled), the error string "ssl disabled on server" will be returned.
• ssl_verify: if true, then verifies the validity of the server SSL certificate (default to false).
• compact_arrays: true to use array-of-arrays structure for the result set, rather than the default array-of-hashes structure.

db:set_timeout(time)

Sets the timeout (in ms) protection for subsequent operations, including the connect method.

db:close() -> 1 | nil,err

Closes the current mysql connection and returns the status.

db:send_query(query) -> bytes | nil,err

Sends the query to the remote MySQL server without waiting for its replies.

Returns the bytes successfully sent out. Use read_result() to read the replies.

db:read_result([nrows]) -> res | nil,err,errcode,sqlstate

Reads in one result returned from the server.

It returns a Lua table (res) describing the MySQL OK packet or result set packet for the query result.

For queries corresponding to a result set, it returns an array holding all the rows. Each row holds key-value pairs for each data fields. For instance,

    {
        { name = "Bob", age = 32, phone = ngx.null },
        { name = "Marry", age = 18, phone = "10666372"}
    }

For queries that do not correspond to a result set, it returns a Lua table like this:

    {
        insert_id = 0,
        server_status = 2,
        warning_count = 1,
        affected_rows = 32,
        message = nil
    }

If more results are following the current result, a second err return value will be given the string again. One should always check this (second) return value and if it is again, then she should call this method again to retrieve more results. This usually happens when the original query contains multiple statements (separated by semicolon in the same query string) or calling a MySQL procedure. See also Multi-Resultset Support.

In case of errors, this method returns at most 4 values: nil, err, errcode, and sqlstate. The err return value contains a string describing the error, the errcode return value holds the MySQL error code (a numerical value), and finally, the sqlstate return value contains the standard SQL error code that consists of 5 characters. Note that, the errcode and sqlstate might be nil if MySQL does not return them.

The optional argument nrows can be used to specify an approximate number of rows for the result set. This value can be used to pre-allocate space in the resulting Lua table for the result set. By default, it takes the value 4.

db:query(query, [nrows]) -> res, err, errcode, sqlstate

This is a shortcut for combining the send_query call and the first read_result call.

You should always check if the err return value is again in case of success because this method will only call read_result only once for you. See also Multi-Resultset Support.

db:server_ver() -> s

Returns the MySQL server version string, like "5.1.64".

You should only call this method after successfully connecting to a MySQL server, otherwise nil will be returned.

db:set_compact_arrays(true|false)

Sets whether to use the "compact-arrays" structure for the resultsets returned by subsequent queries. See the compact_arrays option for the connect method for more details.

mysql.quote(s) -> s

Quote literal string to be used in queries.

Multiple result set support

For a SQL query that produces multiple result-sets, it is always your duty to check the 'again' error message returned by the query, and keep pulling more result sets by calling the read_result() until no 'again' error message returned (or some other errors happen).

Limitations

Authentication

By default, of all authentication methods, only Old Password Authentication(mysql_old_password) and Secure Password Authentication(mysql_native_password) are suppored.

TODO

• implement the MySQL binary row data packets.
• implement MySQL server prepare and execute packets.
• implement the data compression support in the protocol.