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There are different ways to open a connection and to get data.
Prepare database with a table
db <- rocker::newDB() # New database handling object
#> dctr | New object
db$setupSQLite(dbname = tempfile()) # Setup SQLite database
#> Dctr | Driver load RSQLite
db$connect() # Open connection
#> DCtr | Database connected
db$writeTable("mtcars", mtcars) # Create table for testing
#> DCtr | Write table mtcars columns mpg, cyl, disp, hp, drat, wt, qsec, vs, am, gear, carb rows 32
db$disconnect() # Close connection
#> Dctr | Database disconnected
Example 1
Get query with automatic connection / disconnection
output <- db$getQuery("SELECT * FROM mtcars;") # Get query
#> DCtr | Database connected
#> DCtR | Send query 21 characters
#> DCtR | Fetch rows all -> Received 32 rows, 11 columns, 4824 bytes
#> DCtR | Rows fetched 32
#> DCtR | Has completed yes
#> DCtr | Clear result
#> Dctr | Database disconnected
Example 2
Get query with manual connection / disconnection
db$connect() # Open connection
#> DCtr | Database connected
output1 <- db$getQuery("SELECT * FROM mtcars;") # Get query 1
#> DCtR | Send query 21 characters
#> DCtR | Fetch rows all -> Received 32 rows, 11 columns, 4824 bytes
#> DCtR | Rows fetched 32
#> DCtR | Has completed yes
#> DCtr | Clear result
output2 <- db$getQuery("SELECT * FROM mtcars;", 15) # Get query 2
#> DCtR | Send query 21 characters
#> DCtR | Fetch rows 15 -> Received 15 rows, 11 columns, 3416 bytes
#> DCtR | Rows fetched 15
#> DCtR | Has completed no
#> DCtR | Fetch rows 15 -> Received 15 rows, 11 columns, 3416 bytes
#> DCtR | Rows fetched 30
#> DCtR | Has completed no
#> DCtR | Fetch rows 15 -> Received 2 rows, 11 columns, 2184 bytes
#> DCtR | Rows fetched 32
#> DCtR | Has completed yes
#> DCtr | Clear result
db$disconnect() # Close connection
#> Dctr | Database disconnected
Example 3
Function getQuery() is a combination of functions sendQuery(), fetch() and clearResult().
db$connect() # Open connection
#> DCtr | Database connected
db$sendQuery("SELECT * FROM mtcars;") # Send query
#> DCtR | Send query 21 characters
output <- db$fetch() # Fetch result
#> DCtR | Fetch rows all -> Received 32 rows, 11 columns, 4824 bytes
db$clearResult() # Clean up result
#> DCtr | Clear result
db$disconnect() # Close connection
#> Dctr | Database disconnected
Clean up
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.