Java Doc for BindVariable.java in  » Development » JoSQL » org » josql » expressions » Java Source Code / Java DocumentationJava Source Code and Java Documentation

• Named - a named bind variable is prefixed with ":", the value of the variable is set in the Query object via: Query.setVariable(StringObject) . The parser used (javacc generated) is a little picky about "reserved keywords" and as such you cannot use the following as the names of bind variables: select, from, limit, execute, on, all, results, where, having, order, by, group. If you must use one of reserved names then suffix it with "$", i.e. "execute$", "limit$" and so on.
• Anonymous - an anonymous bind variable is represented as "?". The value of the variable is set in the Query object via: Query.setVariable(intObject) . Anonymous variables are assigned an internal integer index starting at 1 and they increase by 1.
• Special - there are 3 types of "special" bind variable:
  • :_currobj - Indicates the current object within the execution scope.
  • :_allobjs - Indicates the current set of objects within the execution scope.
  • :_query - Indicates the Query object.
  • :_grpby - Indicates the Group By object. If there are more than 1 group by objects then :_grpby1 ... :_grpby2 ... :_grpbyX can be used to identify which group by object you mean. Remember that the group by object only has meaning if there is a group by statement.
  • :_grpbys - Indicates the set of group bys, this will be a list of lists, one list for each group by key, and each group by column will be in that list.
  • :_groupby - A synonym for :_grpby.
  • :_groupbys - A synonym for :_grpbys.

  Special bind variables are mainly used in function calls however they can also be used just about anywhere.

Examples

 SELECT :_query,
 :_allobjs,
 :_currobj
 FROM java.lang.Object
 SELECT name
 FROM   java.io.File
 WHERE  length(:_currobj, name) > :length
 AND    length > avg(:_query,:_allobjs,length)
 AND    path LIKE '%' + ?
 

Accessors

It is also possible for bind variables (including the special variables) to have accessors. For example:

 SELECT :_query.variables
 FROM   java.lang.Object
 

Would cause all the bind variables in the query to be returned. Also, if the ? in the next query is an instance of java.lang.String.

 SELECT ?.length
 FROM   java.lang.Object