Xform function

The standardize function checks whether any smirks in the std smirks table, when used in the xform function, results in a modification of the input SMILES stored in NEW.smiles. If the xform function does return a transformed SMILES, then that transformed value is used in place of the value the user attempted to insert. Finally, the trigger is created using the standardized function to possibly modify any SMILE before inserting or updating a table. 

The unimolecular form of the xform function will not properly work with this SMIRKS. Instead, an alternate form that requires an array of SMILES is used. The following SQL... 

Many other uses of the xform function are possible. Because the function is an extension of SQL, it can be easily used with all the other features of the SQL language and capabilities of an RDBMS. 

Suppose it is decided that the valence 5, noncharge-separated representation of the nitro group is to be used throughout the database. The SMIRKS [0 2]=[N+ 1][0- 3] [0 2]=[N+0 1]=[0+0 3], when applied to any charge-separated nitro group will transform it into the proper form. This is accomplished by creating another new SQL function, xform(smiles, smarts). As with the cansmiles and matches functions, this is an extension to standard SQL. Some form of this transformation function is... 

The CHORD6 chemical cartridge is a commercial product from gNova, Inc. It is written using C functions and the OEChem toolkit from OpenEye. It provides the core functions discussed in this book, such as cansmiles, matches, count matches, list matches, smiles to molfile, molfile to smiles, and xform. CHORD makes it possible to efficiently process RDBMS tables containing many millions of chemical structures. 

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