DBI (version 0.1-10)

dbGetInfo-methods: Database interface meta-data

Description

Extract meta-data associated with various objects

Usage

dbGetInfo(dbObj, ...)       # meta-data for any DBIObject
  dbGetDBIVersion()           # DBI version 
  dbGetStatement(res, ...)    # statement that produced result "res"
  dbGetRowCount(res, ...)     # number of rows fetched so far
  dbGetRowsAffected(res, ...) # number of affected rows (e.g., DELETE)
  dbColumnInfo(res, ...)      # result set data types
  dbHasCompleted(res, ...)    # are there more rows to fetch on "res"?

Arguments

dbObj

any object that implements some functionality in the R/S-Plus interface to databases (a driver, a connection or a result set).

res

refers to a DBIResult object.

...

driver-specific arguments.

Value

• dbGetDBIVersion returns a character string with the version of the database interface API.

  dbGetInfo produces either a character vector or a named list of (name, value) pairs.

  dbGetStatement returns a character string with the statement associated with the result set res.

  dbGetRowCount returns the number of rows fetched so far.

  dbGetRowsAffected returns the number of affected rows (e.g., how many rows were deleted, inserted). Some drivers may set this to the total number of rows a query produces.

  dbColumnInfo returns a data.frame with one row per output field in res. The columns should report field name, field data type, scale and precision (as understood by the DBMS engine), whether the field can store NULL values, and possibly other DBMS-specific information.

  dbHasCompleted returns a logical describing whether the operations has been completed by the DBMS or not.

Note

Meta-data associated with a driver should include the version of the package, plus the version of the underlying client library. Connection objects should report the version of the DBMS engine, database name, user, possibly password, etc. Results should include the statement being executed, how many rows have been fetched so far (in the case of queries), how many rows were affected (deleted, inserted, changed, or total number of records to be fetched).

Details

These functions implement a minimal set of meta-data describing the most important aspects of the R/S-Plus to DBMS interface.

The dbGetInfo works very similarly to the function options in that it attempts to extract what the user may request, possibly NULL if it can't locate the specific piece of meta-data.

References

See the Database Interface definition document DBI.pdf in the base directory of this package or http://developer.r-project.org/db.

See Also

dbDriver, dbConnect, dbSendQuery, dbGetQuery, fetch, dbCommit, dbGetInfo, dbListTables, dbReadTable.

Examples

drv <- dbDriver("SQLite")
con <- dbConnect(drv)

dbListTables(con)

rs <- dbSendQuery(con, query.sql)
dbGetStatement(rs)
dbHasCompleted(rs)

info <- dbGetInfo(rs)
names(dbGetInfo(drv))  

# DBIConnection info
names(dbGetInfo(con))

# DBIResult info
names(dbGetInfo(rs))

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