metaData {RMySQL}R Documentation

R/S database interface meta-data

Description

Extract meta-data associated with various objects

Usage

getInfo(dbObject, what)      # meta-data for any dbObject
getConnection(what, ...)

getConnections(mgr)          # meta-data for dbManager objects
getDatabases(obj, ...)       
getTables(obj, dbname, row.names, ...)
getVersion(obj, ...)
getTableIndices(res, table, dbname, ...)

getCurrentDatabase(con)      # meta-data for dbConnection objects
getException(con, ...)
getResultSets(con, ...)
getTableFields(res, table, dbname, ...)

getStatement(res)             # meta-data for dbResultSet objects
getFields(res, ...)
hasCompleted(res, ...)
getRowCount(res, ...)
getRowsAffected(res, ...)
getNullOk(res, ...)

Arguments

dbObject any object that implements some functionality in the R/S interface to databases (e.g., dbManager, dbConnection, dbResultSet).
mgr refers to a dbManager object.
con refers to a dbConnection object.
rs refers to a dbResultSet object.
dbname refers to a database name (instance) on the server.
table refers to a table name in either the current database or in dbname.

Details

These functions implement a minimal set of more or less obvious meta-data describing the most important aspects of the R/S to RDBMS interface.

The getInfo 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.

Value

either a character vector or a named list of meta-data objects.

References

See the Omega Project for Statistical Computing at http://www.omegahat.org for more details on the R/S database interface.

See Also

On database managers:

dbManager MySQL load unload

On connections, SQL statements and resultSets:

dbExecStatement dbExec fetch quickSQL

On transaction management:

commit rollback

On meta-data:

describe getVersion getDatabases getTables getFields getCurrentDatabase getTableIndices getException getStatement hasCompleted getRowCount getAffectedRows getNullOk getInfo

Examples

m <- dbManager(dbms)

# Extract meta-data information.  What MySQL databases are there 
# available on host "wyner"

> getDatabases(m, host = "wyner")
   Database 
1     mysql
2      opto
3      test
4 iptraffic
5     fraud

# What tables are there in the Oracle "opto" database? 

> dbTables(m, dbname = "opto", host = "wyner")
  Tables in opto 
1           PBCT
2          PURGE
3             WL
4          liv25
5          liv85

# let's look at some result set meta-data

> con <- dbConnect(m)
> rs <- dbExecStatement(con, query.sql)

> getStatement(rs)
[1] "show tables"

> hasCompleted(rs)
[1] 0

> getRowCount(rs)
[1] 3

> info <- getInfo(rs)
> names(info)
[1] "statement"     "isSelect"        "rowsAffected"     
[4] "rowCount"     "completed"    "fieldDescription"
> getStatement(rs)
[1] "show tables"

# the following are pieces of meta-data associated with 
# the R/S DBI implementation, versions for the various pieces 
# of software (client, server, interface), etc.

# dbManager object

> names(getInfo(m))  
[1] "connectionIds"     "fetch_default_rec"
[3] "managerId"         "length"           
[5] "num_con"           "counter"          
[7] "clientVersion"    

#  dbConnection object

> names(getInfo(con))
[1] "host"            "user"           
[3] "dbname"          "conType"        
[5] "serverVersion"   "protocolVersion"
[7] "threadId"        "rsId"           

# resultSet object

> names(getInfo(rs)) 
[1] "statement"        "isSelect"        
[3] "rowsAffected"     "rowCount"        
[5] "completed"        "fieldDescription"
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