dbCommit-methods
說明：在Oracle里事務的提交和回滾
使用方法：
dbCommit(conn, ...)
dbRollback(conn, ...)
舉例：
drv <-dbDriver("Oracle")
con <- dbConnect(drv,"scott", "tiger")
dbReadTable(con,"EMP")
rs <- dbSendQuery(con,"delete from emp where deptno = 10")
dbReadTable(con,"EMP")
if(dbGetInfo(rs, what ="rowsAffected") > 1)
{
warning("dubious deletion-- rolling back transaction")
dbRollback(con)
}
dbReadTable(con,"EMP")
dbConnect-methods
說明：創建一個數據庫連接方法
使用方法：
## S4 method for signature 'OraDriver'
dbConnect(drv, username = "",password = "", dbname = "", prefetch = FALSE,
bulk_read = 1000L, stmt_cache = 0L,external_credentials = FALSE,sysdba = FALSE, ...)
## S4 method for signature 'ExtDriver'
dbConnect(drv, prefetch = FALSE, bulk_read= 1000L, stmt_cache = 0L,
external_credentials = FALSE, sysdba =FALSE, ...)
## S4 method for signature 'OraConnection')
dbDisconnect(conn, ...
參數說明：
drv: OraDriver 或 ExtDriver 驅動
conn: 連接oracle對象
username: 數據庫用戶名
password: 數據庫用戶密碼
dbname: 連接oracle數據庫 tns的別名
prefetch: 一個邏輯值，TRUE或FALSE。當設置為TRUE，ROracle會 使用OCI預取緩沖器，以從服務器中檢索附加數據，從而節省通過從OCI提取數據分配一個行緩沖區獲取的RODBI/ ROOCI所需的內存。在使用預取結果取的每一行。通過默認情況下，預取為FALSE且數組提取用於檢索從所述數據服務器。
bulk_read: 一個整數值，表示每次提取的行數。默認 值1000L。當選擇了預取的選項，內存分配用於 預取緩沖器和每次每次會取的行數。當預取 不使用（默認值），內存是分配在RODBI/ ROOCI定義緩沖區。將其設置為一個較大的值會導致分配更多的內存基礎上，在選擇列表中的列和列類型的數量。對於字符類型的列，定義使用最大寬度乘以緩沖區分配 NLS的最大寬度。應用程序應該調整基礎上，該值查詢結果和更大的值將有利於返回大結果的查詢。一個應用程序可以調整為所需要的值。
stmt_cache: 一個整數值，表示語句高速緩存的個數。這意味着游標不需要再次解析就能准備使。默認值是0L。如果stmt_cache值大於0L，則預取的值必須設置為TRUE。
external_credentials: 一個邏輯值，TRUE或FALSE。當設置為TRUE，ROracle會開始OCI會話連接外部憑證進行身份驗證。 缺省值是FALSE。
sysdba: 一個邏輯值，TRUE或FALSE。當設置為TRUE，ROracle會 首先在連接上SYSDBA權限OCI會話。默認 值為FALSE。
舉例：
## 在本機創建一個數據庫實例和連接
drv <-dbDriver("Oracle")
con <- dbConnect(drv,username = "scott", password = "tiger")
## 運行一個SQL語句
rs <- dbSendQuery(con,"select * from emp where deptno = 10")
## 讀取一個結果集到數據框
data <- fetch(rs) ## extractall rows
dim(data)
## 在連接遠程數據庫的方法：
## create an Oracle Databaseinstance and create one connection to a
## remote database using theSID in the connect string.
drv <-dbDriver("Oracle")
## refer to Oracle Database NetServices Administator's Guide for
## details on connect stringspecification.
host <- "myhost"
port <- 1521
sid <- "mysid"
connect.string <- paste(
"(DESCRIPTION=",
"(ADDRESS=(PROTOCOL=tcp)(HOST=",host, ")(PORT=", port, "))",
"(CONNECT_DATA=(SID=",sid, ")))", sep = "")
## use username/passwordauthentication
con <- dbConnect(drv,username = "scott", password = "tiger",
dbname = connect.string)
## run a SQL statement bycreating first a resultSet object
rs <- dbSendQuery(con,"select * from emp where deptno = 10")
## we now fetch records fromthe resultSet into a data.frame
data <- fetch(rs) ## extractall rows
dim(data)
dbDriver-methods
說明：Oracle驅動的初始化和關閉
使用方法：
## S4 method for signature 'OraDriver'
dbUnloadDriver(drv, ...)
## S4 method for signature 'ExtDriver'
dbUnloadDriver(drv, ...)
舉例：
# create an Oracle instance
drv <-dbDriver("Oracle")
con <- dbConnect(drv,"scott", "tiger")
res <- dbSendQuery(con,"select * from emp")
fetch(res, n = 5)
fetch(res)
dbClearResult(res)
dbUnloadDriver(drv)
dbGetInfo-methods
說明：獲取對象的信息的函數
舉例：
drv <-dbDriver("Oracle")
con <- dbConnect(drv,"scott", "tiger")
rs <- dbSendQuery(con,"select * from emp")
dbGetStatement(rs)
dbHasCompleted(rs)
dbGetInfo(rs)
# DBIDriver info
names(dbGetInfo(drv))
# DBIConnection info
names(dbGetInfo(con))
# DBIResult info
names(dbGetInfo(rs))
dbListConnections-methods
說明：獲取連接對象的信息的函數
使用方法：
## S4 method for signature 'OraDriver'
dbListConnections(drv, ...)
## S4 method for signature 'ExtDriver'
dbListConnections(drv, ...)
## S4 method for signature 'OraConnection'
dbListResults(conn, ...)
舉例：
drv <-dbDriver("Oracle")
con1 <- dbConnect(drv,"scott", "tiger")
res1 <- dbSendQuery(con1,"select * from emp where deptno = 10")
res2 <- dbSendQuery(con1,"select * from emp where deptno = 20")
con2 <- dbConnect(drv,"scott", "tiger")
res3 <- dbSendQuery(con2,"select * from dept")
## get all active statements
for(con indbListConnections(drv))
for (res in dbListResults(con))
print(dbGetStatement(res))
dbReadTable-methods
說明：在數據庫中執行get, assign,exists, remove, objects, and names except的操作
使用方法：
## S4 method for signature'OraConnection,character'
dbReadTable(conn, name, schema = NULL,row.names = NULL, ...)
## S4 method for signature'OraConnection,character,data.frame'
dbWriteTable(conn, name, value, row.names =FALSE, overwrite = FALSE,
append = FALSE, ora.number = TRUE, schema =NULL, ...)
## S4 method for signature'OraConnection,character'
dbExistsTable(conn, name, schema = NULL,...)
## S4 method for signature 'OraConnection,character'
dbRemoveTable(conn, name, purge = FALSE,schema = NULL, ...)
## S4 method for signature 'OraConnection'
dbListTables(conn, schema = NULL, all =FALSE, full = FALSE, ...)
## S4 method for signature'OraConnection,character'
dbListFields(conn, name, schema = NULL,...)
參數說明：
conn: 連接數據庫的對象
name: 數據庫表名（大小寫敏感）
schema: 數據庫用戶（大小寫敏感）
row.names: 在dbReadTable情況下，這個變量可以是字符串，索引或邏輯矢量指定列中的DBMS表被用作在row.names 輸出data.frame（一個NULL指定的列不應該被用來作為row.names 在輸出中）。默認值為NULL。
在dbWriteTable的情況下，這個參數應該是一個邏輯值，表明是否row.names應該輸出到輸出DBMS表;如果為true，一個名稱是“row.names”額外的列其將被添加到輸出。默認為FALSE。
value: 一個包含數據的寫到表里的data.frame
overwrite: 一個邏輯值，是否覆蓋表中的數據，默認為FALSE
append: 一個邏輯值，是否是追加數據到已存在的表，默認為FALSE
ora.number: 一個邏輯值，指明是否要創建一個表與OracleNUMBER或 BINARY_DOUBLE列當在寫數字數據時。默認值為TRUE。
purge: 邏輯值，指明是否將purge:選項添加到SQL DROPTABLE語句中。
all: 邏輯值，是否查看所有schemas
full: 邏輯值，指明是否生成schema名。當參數都是TRUE時，輸出是一個包含模式名向量，其次是表名。在輸出用矩陣（...，NCOL= 2）產生一個矩陣其中每一行對應於一個表中，列表示的模式名和表名
ROracle methods such asdbReadTable, dbGetQuery, fetch, and dbWriteTable use the following mapping between R andOracle data types:
● logical and integer map to Oracle INTEGER
● numeric maps to Oracle NUMBER if argument ora.number is TRUE orOracle BINARY_DOUBLEif FALSE
● character maps to Oracle VARCHAR2(4000)
● Date and POSIXct map to Oracle DATE ROracle - the ROracle package R- the R application POSIXct - the POSIXct class TIMESTAMP TIMESTAMP WITH TIMEZONE TIMESTAMP WITH LOCAL TIME ZONE
● difftime maps to Oracle INTERVAL DAY TO SECOND
● list of raw vectors map to Oracle RAW(2000)
● other R types such as factor are converted to character
舉例：
con <- dbConnect(Oracle(),"scott", "tiger")
if (dbExistsTable(con,"FOO", "SCOTT"))
dbRemoveTable(con,"FOO")
foo <- dbReadTable(con,"EMP")
row.names(foo) <- foo$EMPNO
foo <- foo[,-1]
dbWriteTable(con,"FOO", foo, row.names = TRUE)
dbWriteTable(con,"FOO", foo, row.names = TRUE, overwrite = TRUE)
dbReadTable(con,"FOO", row.names = 1)
dbGetQuery(con, "deletefrom foo")
dbWriteTable(con,"FOO", foo, row.names = TRUE, append = TRUE)
dbReadTable(con,"FOO", row.names = 1)
dbRemoveTable(con,"FOO")
dbListTables(con)
dbListFields(con,"EMP")
if (dbExistsTable(con,"RORACLE_TEST", "SCOTT"))
dbRemoveTable(con,"RORACLE_TEST")
# example of POSIXct usage
# A table is created using:
createTab <- "createtable RORACLE_TEST(row_num number, id1 date,
id2 timestamp, id3 timestampwith time zone,
id4 timestamp with local timezone )"
dbGetQuery(con, createTab)
# Insert statement
insStr <- "insert intoRORACLE_TEST values(:1, :2, :3, :4, :5)";
# Select statement
selStr <- "select *from RORACLE_TEST";
# Insert time stamp withouttime values in POSIXct form
x <- 1;
y <- "2012-06-05";
y <- as.POSIXct(y);
dbGetQuery(con, insStr,data.frame(x, y, y, y, y));
# Insert date & times stampwith time values in POSIXct form
x <- 2;
y <- "2012-01-0507:15:02";
y <- as.POSIXct(y);
z <- "2012-01-0507:15:03.123";
z <- as.POSIXct(z);
dbGetQuery(con, insStr,data.frame(x, y, z, z, z));
# Insert list of date objectsin POSIXct form
x <- c(3, 4, 5, 6);
y <- c('2012-01-05','2011-01-05', '2013-01-05', '2020-01-05');
y <- as.POSIXct(y);
dbGetQuery(con, insStr,data.frame(x, y, y, y, y));
dbCommit (con)
# Selecting data and displayingit
res <- dbGetQuery(con,selStr)
res[,1]
res[,2]
res[,3]
res[,4]
res[,5]
dbSendQuery-methods
說明：查詢返回數據庫的結果集
舉例：
drv <-dbDriver("Oracle")
con <- dbConnect(drv,"scott", "tiger")
res <- dbSendQuery(con,"select * from emp where deptno = :1",
data = data.frame(deptno = 10))
data <- fetch(res, n = -1)
res2 <- dbSendQuery(con,"select * from emp where deptno = :1",
data1 = data.frame(deptno =10), prefetch=TRUE,
bulk_read=2L)
data1 <- fetch(res2, n = -1)
res3 <- dbSendQuery(con,"select * from emp where deptno = :1",
data2 = data.frame(deptno =10), bulk_read=10L)
data2 <- fetch(res3, n = -1)
res4 <- dbSendQuery(con,"select * from emp where ename = :1",
data3 = data.frame(ename ='SMITH'))
data3 <- fetch(res4, n = -1)