# Mysql客户端
lua-resty-mysql是为基于cosocket API的ngx\_lua提供的Lua Mysql客户端，通过它可以完成Mysql的操作。默认安装OpenResty时已经自带了该模块，使用文档可参考[https://github.com/openresty/lua-resty-mysql](https://github.com/openresty/lua-resty-mysql)。
## 1. 编辑mysql/test_mysql.lua
```
local function close_db( db )
if not db then
return
end
db:close()
end
local mysql = require("resty.mysql")
-- 创建实例
local db, err = mysql:new()
if not db then
ngx.say("new mysql error:", err)
return
end
-- 设置超时时间(毫秒)
db:set_timeout(5000)
local props = {
host = "172.19.237.44",
port = 3306,
database = "fuhuitest",
user = "root",
password = "wsy@123456"
}
local res, err, errno, sqlstate = db:connect(props)
if not res then
ngx.say("connect to mysql error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
-- 删除表
local drop_table_sql = "drop table if exists test"
res, err, errno, sqlstate = db:query(drop_table_sql)
if not res then
ngx.say("drop table error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
-- 创建表
local create_table_sql = "create table test(id int primary key auto_increment, ch varchar(100))"
res, err, errno, sqlstate = db:query(create_table_sql)
if not res then
ngx.say("create table error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
-- 插入
local insert_sql = "insert into test (ch) values('hello')"
res, err, errno, sqlstate = db:query(insert_sql)
if not res then
ngx.say("insert error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
res, err, errno, sqlstate = db:query(insert_sql)
ngx.say("insert rows : ", res.affected_rows, " , id : ", res.insert_id, "<br/>")
-- 更新
local update_sql = "update test set ch = 'hello2' where id =" .. res.insert_id
res, err, errno, sqlstate = db:query(update_sql)
if not res then
ngx.say("update error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
ngx.say("update rows : ", res.affected_rows, "<br/>")
-- 查询
local select_sql = "select id, ch from test"
res, err, errno, sqlstate = db:query(select_sql)
if not res then
ngx.say("select error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
for i, row in ipairs(res) do
for name, value in pairs(row) do
ngx.say("select row ", i, " : ", name, " = ", value, "<br/>")
end
end
ngx.say("<br/>")
--防止sql注入
local ch_param = ngx.req.get_uri_args()["ch"] or ''
--使用ngx.quote_sql_str防止sql注入
local query_sql = "select id, ch from test where ch = " .. ngx.quote_sql_str(ch_param)
res, err, errno, sqlstate = db:query(query_sql)
if not res then
ngx.say("select error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
for i, row in ipairs(res) do
for name, value in pairs(row) do
ngx.say("select row ", i, " : ", name, " = ", value, "<br/>")
end
end
-- 删除
local delete_sql = "delete from test"
res, err, errno, sqlstate = db:query(delete_sql)
if not res then
ngx.say("delete error : ", err, " , errno : ", errno, " , sqlstate : ", sqlstate)
return close_db(db)
end
ngx.say("delete rows : ", res.affected_rows, "<br/>")
close_db(db)
```
对于新增/修改/删除会返回如下格式的响应：
```
{
insert_id = 0,
server_status = 2,
warning_count = 1,
affected_rows = 32,
message = nil
}
```
affected\_rows表示操作影响的行数，insert\_id是在使用自增序列时产生的id。
对于查询会返回如下格式的响应：
```
{
{ id= 1, ch= "hello"},
{ id= 2, ch= "hello2"}
}
```
null将返回ngx.null。
## 2. openResty.conf配置文件
```
location /lua_mysql {
default_type 'text/html';
lua_code_cache on;
content_by_lua_file /usr/openResty/lua/mysql/test_mysql.lua;
}
```
## 3. 访问如http://127.0.0.1/lua_mysql?ch=hello进行测试，得到如下结果
```
insert rows : 1 , id : 2
update rows : 1
select row 1 : ch = hello
select row 1 : id = 1
select row 2 : ch = hello2
select row 2 : id = 2
select row 1 : ch = hello
select row 1 : id = 1
delete rows : 2
```
客户端目前还没有提供预编译SQL支持（即占位符替换位置变量），这样在入参时记得使用ngx.quote\_sql\_str进行字符串转义，防止sql注入；连接池和之前Redis客户端完全一样就不介绍了。
<br />
对于Mysql客户端的介绍基本够用了，更多请参考[https://github.com/openresty/lua-resty-mysql](https://github.com/openresty/lua-resty-mysql)。
