Domain SMILES

Create Domain smiles As Text Check (valid(Value)) ... 

The descriptor was a product of the correlation weights, CW(Ik), calculated by the Monte Carlo method for each kth element of a special SMILES-like notation introduced by the authors. The notation codes the following characteristics the atom composition, the type of substance (bulk or not, ceramic or not), and the temperature of synthesis. The QSAR model constructed in this way was validated with the use of many different splits into training (n 21) and validation (n=8) sets. Individual sub-models are characterized by high goodness-of-fit (0.972 applicability domain of the model, it is not known if all the compounds (metal oxides, nitrides, mullite, and silicon carbide) can be truly modeled together. 

The SQL domain allows one to define which values are to be allowed in a particular column of a table. A domain is created by stating the underlying built-in SQL data type used to store the domain data type. In addition, a check constraint function may be used to allow or forbid certain values. This can be used to great advantage for SMILES and canonical SMILES. Using a domain improves the ability of the RDBMS to maintain the integrity of the data contained in its tables. 

The following SQL defines a domain data type smiles. 

The use of the keyword Value is required. Value refers to the value of the data element, here the SMILES. Once this domain is created, it can be used as a data type in the creation of a table. For example ... 

Using a domain like this, the smiles data type behaves much like a standard data type. When one attempts to insert an invalid number into a numeric column, an SQL error is reported and the value is not inserted. This fundamental behavior of an RDBMS is readily extended to SMILES using a domain. 

It might also be useful to define a canonical SMILES domain. This could be done as follows ... 

Using a domain ensures that only appropriate data can be inserted into a column. If an attempt is made to insert invalid data, an error is reported. The user is then responsible for correcting the value, if possible and trying the insert again. The SQL trigger mechanism automates this process. The following SQL will not only ensure that the cansmi column contains canonical SMILES, it will correct problems where possible. 

Why use the domain to define a smiles data type, but use a trigger for canonical SMILES First, SMILES is either valid or not. It is not feasible to... 

Even though chemical stmctures are reported in many of the public domain and cotmnercially available databases described above, they are not readily available for download as stracture files, for instance in. MOL2 or Stmcture data format (.SDF). Nonetheless, there is software available that can convert stracture names, SMILES, SMARTS, or InChl notation into molecular or structural files. This is discussed in the next section of this chapter. 

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