1. A method, comprising: repeatedly triggering a User Defined Function (UDF) that generates a data stream; applying, with a computer, a data continuous Structured Query Language (SQL) query to the data stream to construct a data continuous SQL process (DCSP); modeling the DCSP as a graph of stations specified with triggering conditions and outgoing pipes, the outgoing pipes defined with a relation schema for type-preservation and with a stream key for identifying stream elements, wherein relations returned from the UDF are replicated to multiple pipes for multiple destination stations; and executing, in a database engine located in a database, the DCSP, wherein the UDF includes relational operators in the SQL query and expresses a relational transformation since the UDF includes an input value as a relation and an output value as a relation.
1. A method, comprising: repeatedly triggering a User Defined Function (UDF) that generates a data stream; applying, with a computer, a data continuous Structured Query Language (SQL) query to the data stream to construct a data continuous SQL process (DCSP); modeling the DCSP as a graph of stations specified with triggering conditions and outgoing pipes, the outgoing pipes defined with a relation schema for type-preservation and with a stream key for identifying stream elements, wherein relations returned from the UDF are replicated to multiple pipes for multiple destination stations; and executing, in a database engine located in a database, the DCSP, wherein the UDF includes relational operators in the SQL query and expresses a relational transformation since the UDF includes an input value as a relation and an output value as a relation. 5. The method of claim 1 , wherein the DCSP is data-stream driven and continuously running.