R语言学习笔记——RMySQL基本操作

# 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

mysql> select * from t_user;
+----+-----------+
| id | user      |
+----+-----------+
|  1 | A1        |
|  2 | B1        |
|  3 | fens.me   |
|  5 | 你好      |
|  4 | 小朋友    |
|  6 | 正确了    |
+----+-----------+

> users <- dbGetQuery(conn, "select * from t_user");
> users
id    user
1  1      A1
2  2      B1
3  3 fens.me
4  5      ??
5  4     ???
6  6     ???

> conn <- dbConnect(m, user = "root", password = "144230", dbname = "test", host="localhost.localdomain")
> dbSendQuery(conn,'SET NAMES gbk')
<MySQLResult:(9246,3,0)>
> users <- dbGetQuery(conn, "select * from t_user");
> users
id    user
1  1      A1
2  2      B1
3  3 fens.me
4  5      ??
5  4     ???
6  6     ???
> query <- dbSendQuery(conn, "SELECT * FROM t_user")
> data <- fetch(query, n = -1)
> mysqlCloseResult(query)
[1] TRUE
> data
id               user
1  1                 A1
2  2                 B1
3  3            fens.me
4  5   \xc4\xe3\xba\xc3
5  4 С\xc5\xf3\xd3\xd1
6  6    \xd5\xfdȷ\xc1\xcb