While looking for java libraries to build queries in a database agnostic way I came across many including iciql, querydsl, jooq, joist, hibernate etc.
I wanted something that does not require configuration files and can work with dynamic schemas. For my application, I come to know about the database and the schema at runtime so I won't have any configuration files or domain classes for the schema.
This seems to be one of the core goals of querydsl but going through the documentation for querydsl I see a lot of examples for building dynamic queries using domain classes but I have not come across anything that explains how to build such database agnostic queries using just the dynamic information I have about the schema.
Jooq offers such functionality(See: http://www.jooq.org/doc/3.2/manual/getting-started/use-cases/jooq-as-a-standalone-sql-builder/) but have a restrictive license if I want to expand my focus to Oracle or MS SQL(Which I may not love but need to support).
Can someone with experience in querydsl let me know if such a thing is possible with querydsl, and if yes, how.
If someone know of any other too which can satisfy my requirements, it would be really appreciated.
A very simple SQL query such as this:
...can be created dynamically like this (without any sugar added):
Here is a small variation of ponzao's solution using PathBuilder
Update: Timo has invalidated my original response by showing me how to do what I want WITHOUT having to replace the SQLQuery class. Here is his comment:
I have removed my unnecessary class. Here is an example of using SQLQuery directly to get the SQL string WITHOUT executing the query (e.g., without using the
list
method):This response answers how to use QueryDSL to build out a complete SQL query without actually executing the query. It does not address your additional requirements about "dynamic schemas" and "without domain objects"...