R语言：R操作RMySQL

1). RMySQL辅助操作

加载类库
> library(RMySQL)

建立本地连接
> conn <- dbConnect(MySQL(), dbname = "rmysql", username="rmysql", password="rmysql",client.flag=CLIENT_MULTI_STATEMENTS)

建立远程连接
> conn <- dbConnect(MySQL(), dbname = "rmysql", username="rmysql", password="rmysql",host="192.168.1.201",port=3306)

关闭连接
dbDisconnect(conn)

查看数据库的表
> dbListTables(conn)
[1] "t_user"

查看表的字段
> dbListFields(conn, "t_user")
[1] "id"   "user"

查询MySQL信息
> summary(MySQL(), verbose = TRUE)
<MySQLDriver:(23864)>
Driver name:  MySQL
Max  connections: 16
Conn. processed: 3
Default records per fetch: 500
DBI API version:

# MySQL连接实例信息
> summary(conn, verbose = TRUE)
<MySQLConnection:(23864,2)>
User: root
Host: localhost
Dbname: rmysql
Connection type: localhost via TCP/IP
MySQL server version:  5.6.11
MySQL client version:  5.6.11
MySQL protocol version:  10
MySQL server thread id:  35
No resultSet available

# MySQL连接信息
> dbListConnections(MySQL())
[[1]]
<MySQLConnection:(23864,2)> 

2). RMySQL数据库操作

# 建表并插入数据
> t_demo<-data.frame(
a=seq(1:10),
b=letters[1:10],
c=rnorm(10)
)
> dbWriteTable(conn, "t_demo", t_demo)

# 获得整个表数据
> dbReadTable(conn, "t_demo")
a b           c
1   1 a  0.98868164
2   2 b -0.66935770
3   3 c  0.27703638
4   4 d  1.36137156
5   5 e -0.70291017
6   6 f  1.61235088
7   7 g  0.17616068
8   8 h  0.29700017
9   9 i  0.19032719
10 10 j -0.06222173

# 插入新数据
> dbWriteTable(conn, "t_demo", t_demo, append=TRUE)
> dbReadTable(conn, "t_demo")
row_names  a b           c
1          1  1 a  0.98868164
2          2  2 b -0.66935770
3          3  3 c  0.27703638
4          4  4 d  1.36137156
5          5  5 e -0.70291017
6          6  6 f  1.61235088
7          7  7 g  0.17616068
8          8  8 h  0.29700017
9          9  9 i  0.19032719
10        10 10 j -0.06222173
11         1  1 a  0.98868164
12         2  2 b -0.66935770
13         3  3 c  0.27703638
14         4  4 d  1.36137156
15         5  5 e -0.70291017
16         6  6 f  1.61235088
17         7  7 g  0.17616068
18         8  8 h  0.29700017
19         9  9 i  0.19032719
20        10 10 j -0.06222173

# 覆盖原表数据
> dbWriteTable(conn, "t_demo", t_demo, overwrite=TRUE)

# 1). 查询数据
> d0 <- dbGetQuery(conn, "SELECT * FROM t_demo where c>0")
> class(d0)
[1] "data.frame"

> d0
row_names a b         c
1         1 1 a 0.9886816
2         3 3 c 0.2770364
3         4 4 d 1.3613716
4         6 6 f 1.6123509
5         7 7 g 0.1761607
6         8 8 h 0.2970002
7         9 9 i 0.1903272

# 2). 执行SQL脚本查询，并分页
> rs <- dbSendQuery(conn, "SELECT * FROM t_demo where c>0")
> class(rs)
[1] "MySQLResult"
attr(,"package")
[1] "RMySQL"
> mysqlCloseResult(rs)
[1] TRUE

> d1 <- fetch(rs, n = 3)
> d1
row_names a b         c
1         1 1 a 0.9886816
2         3 3 c 0.2770364
3         4 4 d 1.3613716

# 3). 查看集统计信息
> summary(rs, verbose = TRUE)
row_names               a              b                   c
Length:7           Min.   :1.000   Length:7           Min.   :0.1762
Class :character   1st Qu.:3.500   Class :character   1st Qu.:0.2337
Mode  :character   Median :6.000   Mode  :character   Median :0.2970
Mean   :5.429                      Mean   :0.7004
3rd Qu.:7.500                      3rd Qu.:1.1750
Max.   :9.000                      Max.   :1.6124

# 不插入row.names字段
> dbWriteTable(conn, "t_demo", t_demo,row.names=FALSE,overwrite=TRUE)
> dbGetQuery(conn, "SELECT * FROM t_demo where c>0")
a b         c
1 1 a 0.9886816
2 3 c 0.2770364
3 4 d 1.3613716
4 6 f 1.6123509
5 7 g 0.1761607
6 8 h 0.2970002
7 9 i 0.1903272

# 删除表
> if(dbExistsTable(conn,'t_demo')){
+     dbRemoveTable(conn, "t_demo")
+ }
[1] TRUE
执行SQL语句，dbSendQuery

> query<-dbSendQuery(conn, "show tables")
> data <- fetch(query, n = -1)
> data
Tables_in_rmysql
1           t_demo
2           t_user
> mysqlCloseResult(query)
[1] TRUE

4). win的字符集设置
在win7中，向MySQL插入中文

mysql> INSERT INTO t_user(user) values('小朋友'),('你好'),('正确了');
Query OK, 3 rows affected (0.07 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> select * from t_user;
+----+---------+
| id | user    |
+----+---------+
|  1 | A1      |
|  2 | AB      |
|  3 | fens.me |
|  5 | 你好    |
|  4 | 小朋友  |
|  6 | 正确了  |
+----+---------+
6 rows in set (0.07 sec)
通过RMySQL查询

> dbGetQuery(conn, "SELECT * FROM t_user")
id    user
1  1      A1
2  2      AB
3  3 fens.me
4  5      ??
5  4     ???
6  6     ???
设置GKB字符集

> dbDisconnect(conn)
> conn <- dbConnect(MySQL(), dbname = "rmysql", username="root", password="",client.flag=CLIENT_MULTI_STATEMENTS)
> dbSendQuery(conn,'SET NAMES gbk')

> query<-dbSendQuery(conn, "SELECT * FROM t_user")
> data <- fetch(query, n = -1)
> mysqlCloseResult(query)
[1] TRUE
> data
id    user
1  1      A1
2  2      AB
3  3 fens.me
4  5    你好
5  4  小朋友
6  6  正确了