Select schema name

As indicated in Fig. 1. lb, the individual matchers may either be executed sequentially, independently (in parallel), or in some mixed fashion. In the sequential approach, the matchers are not executed independently, but the results of initial matchers are used as input by subsequent matchers. A common strategy, e.g., used in Cupid (Madhavan et al. 2001), is to first execute a linguistic matcher to compare the names of schema elements and then use the obtained similarities as input for structure-based matching. In the parallel matcher strategy, individual matchers are autonomous and can be independently executed from other matchers. This supports a high flexibility to select matchers for execution and combination. Furthermore, these matchers may also physically be executed in parallel, e.g., on multicore or multiserver hardware. On the other hand, the autonomy of individual matchers may introduce redundant computations, e.g., of name similarities to be used for structural matching. The mixed strategy combines sequential and parallel matcher execution and is thus most complex. 

The cid column is a foreign key referencing the idcolumnof the structure table. This prevents any names from being entered that do not have a corresponding entry in the structure table. It also associates the name with the proper structure. As shown in earlier chapters, names, and smiles can be selected from the tables in this schema using the following SQL. 

Insert Into schema.structure (id, name, isosmiles, coords, atoms) Select id, (molfile mol(molfile)). from schema.sdf ... 

As a relational query language, SQL always returns results that are themselves relation instances. Thus, the basic constructs in SQL cooperate in specifying aspects of the schema as well as the instantiation of a query result. Roughly, the SELECT clause specifies the names of attributes to appear in the result, the FROM clause specifies... 

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