如何在R中建立数据库连接/查询以进行单元测试

install.packages("DBI")
install.packages("RMySQL")  # 用于MySQL数据库的驱动程序包
install.packages("RPostgreSQL")  # 用于PostgreSQL数据库的驱动程序包

library(DBI)

# 建立与MySQL数据库的连接
con <- dbConnect(RMySQL::MySQL(), 
                 host = "localhost",
                 port = 3306,
                 user = "username",
                 password = "password",
                 dbname = "database_name")

# 建立与PostgreSQL数据库的连接
con <- dbConnect(RPostgreSQL::PostgreSQL(), 
                 host = "localhost",
                 port = 5432,
                 user = "username",
                 password = "password",
                 dbname = "database_name")

# 执行查询语句
query <- "SELECT * FROM table_name"
result <- dbGetQuery(con, query)

# 处理查询结果
# ...

dbDisconnect(con)