在R的MonetDBLite中使用WHERE子句的问题

Question

I am trying to use MonetDBLite in R64bit 3.5.1. My problem is that I can not filter the data using SQL command like this example:

dbGetQuery(DB,'select * from table1 where "var1" = "1"')

I get this error:

Error in .local(conn, statement, ...) : 
  Unable to execute statement 'select * from table1  where "var1" = "1"'.
Server says 'ParseException:SQLparser:42000!SELECT: identifier '1' unknown'.

Any ideas?

Answer 1

For constant values, you need to use single quotes ( ' ) or none for numeric values. So in your example,

dbGetQuery(DB,'select * from table1 where "var1" = 1') or

dbGetQuery(DB,'select * from table1 where "var1" = \\'1\\'') or

dbGetQuery(DB,"select * from table1 where \\"var1\\" = '1'")

should all work.

The general rule is that identifiers ( table1 or var1 ) generally only need to be quoted with " if they contain spaces or uppercase characters and constants ( 1 ) only need to be quoted with ' if they are character strings.