如何使用R获取唯一的特定表列名称?
示例代码:
df<-dbgetQuery(con,"select * from table 1 limit 100")
colnames(df)
上述查询是否还有其他选择?
答案 0 :(得分:1)
得到解决方案,并使用以下查询获取名称。
dbGetQuery(con,"SELECT column_name
+ FROM information_schema.columns
+ WHERE table_schema = 'your schema'
+ AND table_name = 'table name'") ##ORDER BY ordinal_position; to orderby
示例查询:
dbGetQuery(con,"SELECT column_name, data_type
+ FROM information_schema.columns
+ WHERE table_name = 'data 1'
+ ORDER BY ordinal_position")
两个查询都运行良好。
答案 1 :(得分:0)
为了完整起见,我发布了用于检索表概览+具有类型的表列概览的完整代码:
library(RPostgres)
# login
your_connection <- dbConnect(Postgres(),
host = '*your-host-address*',
port = *your-port-four-digits*,
user = '*your-username*',
password = 'your-password*',
sslmode = 'require',
dbname = '*name-of-database*')
# send request to get overview of tables
res <- dbSendQuery(your_connection, "select distinct table_schema
from information_schema.tables
where table_type ='VIEW'
or table_type ='FOREIGN TABLE'
order by table_schema")
data <- dbFetch(res, n=-1)
dbClearResult(res)
data
# send request to get overview of tables in a table schema
res <- dbSendQuery(your_connection, "select distinct table_name
from information_schema.columns
where table_schema='*your-table-name*'
order by table_name")
data <- dbFetch(res, n=-1)
dbClearResult(res)
data
# send request to get overview of columns of a table
res <- dbSendQuery(your_connection, "select distinct column_name, data_type
from information_schema.columns
where table_name ='*your-table-name*'
order by column_name")
data <- dbFetch(res, n=-1)
dbClearResult(res)
data