You may also need dbQuoteIdentifier() if you are creating tables or relying on user input to choose which column to filter on. This method will automatically take care of dangerous characters in the same way as sqlInterpolate() ( better) and dbBind() ( best). The Overflow Blog On the quantum internet, data doesn’t stream it teleports (Ep. However, if there’s no other way around it, you can use dbQuoteString() to add the quotes for you. Browse other questions tagged r if-statement vectorization r-faq or ask your own question. You need to be extremely careful when doing the escaping yourself, and it’s better to rely on existing code that multiple people have carefully reviewed. If you’re in this unhappy situation, first make absolutely sure that you haven’t missed an existing DBI helper function that does what you need. Sometimes you can’t create the SQL you want using either of the previous methods. # 2 MSY Louis Armstrong New Orleans Intl 29.99339 -90.25803 4 -6 A dbClearResult(airport) airport_sql <- glue_sql("SELECT * FROM airports WHERE faa IN ()", This is useful for the SQL IN Operator for instance. If you place an astersk * at the end of a glue expression the values will be collapsed with commas. The figure below shows the conditional flow chart of an if-statement.: condition should be an expression that evaluates to TRUE or FALSE. An if statement is a good choice here because it allows us to control the code execution depending on the conditional. # 1 GPT Gulfport-Biloxi 30.40728 -89.07011 28 -6 A dbClearResult(airport) An if statement tells the interpreter to run a line of code if a condition returns TRUE. library(glue)Īirport_sql <- glue_sql("SELECT * FROM airports WHERE faa = ?")ĭbFetch(airport) # faa name lat lon alt tz dst The function glue_sql(), part of the the glue package, is able to handle the SQL quoting and variable placement. Parameterized queries are generally the safest and most efficient way to pass user defined values in a query, however not every database driver supports them. These are ordered by the level of safety they provide: if you can use dbSendQuery() and dbBind(), you should.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |