Select where clause

Notice the use of the Where clause, similar to its use in the Select statement. It is important to use Where with Update. Otherwise every row of... 

The results of a Select statement are in the form of a table. This can be a subset of a single table, or the result of joining several tables. The exact set of rows is chosen by using various Where clauses. The use of Boolean operation such as and, or, and not allows a sort of union (or), intersection (and), and difference (not). For example ... 

Notice that each line in the select clause contains columns from only one table. Likewise, each line in the from clause contains one new table name with each table (after the first one) preceded by the join keyword. Each column uses a table name (a table alias) for brevity. Now that all the tables are properly joined, the columns selected can be arranged in any order desired. Some columns can also be removed from the select clause. The compound id and sample id may not be of interest in the final result, since these arbitrary values are used only to maintain relations among the tables. Finally, any additions to the where clause can be added as desired. 

In the SQL examples discussed previously, tables were joined with each other using the on condition to correlate the appropriate rows and a final where clause to restrict the selection of data. Without using the on condition, every row of one table would be joined with every row of the other, resulting in more rows than desired. Sometimes, one wishes to join all rows from one table with all rows from another to result in all possible combinations of rows. Unless the tables are relatively small, this may still result in more rows than desired. For example, in a table of nci.structures containing only 250,000 structures, combining all rows with each other would result in 62,500,000,000 rows Even if a where clause is used to restrict the number of selected rows, it is inefficient (and unnecessary) to produce combinations in this way. 

This SQL statement can be expanded in many different ways to satisfy many different requirements. For example, an additional where clause in the subselect statements could limit selection of reactants by molecular weight, cost, availability, etc. The type of amine or acid chloride could also be selected by changing the SMARTS in the matches function. For example, aromatic amines could be selected by using matches (smiles, c[NHl] ). 

SPARQL queries start with namespace declarations in the PREFIX clause. The SELECT clause identifies the information that should be returned, in this case we specify a variable named supplier. Variables in SPARQL always start with a and can match any node (resource or hteral) in an RDF data graph. The WHERE clause specifies triple patterns that should be matched. A triple pattern is similar to a triple, but any part of it can be replaced by a variable. In the example query (see Listing 3.2), we are interested in all triples of the form ... 

A more complex example query is shown in Listing 3.3. This query returns not only the supplier but also the maximum working hours of mo Engl. Here, SELECT does not specify concrete variables that should be extracted, but rather states that the bindings for both specified variables should be returned in the result set (by Additionally, the WHERE clause now contains a graph pattern created through the conjunction of two triple patterns (through... 

STOP command is used. The WHERE clause of the DISPLAY command Is of the same form as In the SEARCH command and may Include non-structural data as well as structure and substructure search requests. The SEARCH and DISPLAY commands differ in that, while both search the database, save the qualifying registry numbers, and present a "hit count" to the user, the DISPLAY command also displays selected Information at the terminal for each compound. 

The quality plan would be a logical place for such controls to be defined but clause 4.2.3 does not specifically refer to subcontractor controls. Any intention that they be defined in the quality plan is hidden in 4.2.3.1(b) where it requires you to give timely consideration to the identification and acquisition of any controls etc. Some companies produce a Quality Assurance Requirement Specification to supplement ISO 9001 and also produce a Subcontractor Surveillance Plan. In most other cases the controls may be defined on the reverse side of the purchase order as standard conditions coded and selected for individual purchases. 

This statement translates to "Select everything from the table named RXN, where the SMILES field contains the substructure string for benzoic acid as a product". The = clause is an artifact of the data cartridge implementation it does not necessarily mean that only a single occurrence of the benzoic acid substructure should be found. 

Where the natural selectivity of amine solutions is insufficient to produce a Claus gas with the desired sulfur concentration, the sulfur content may be increased by feeding the acid gas from a first stripper to a second absorption stage where the H2S is absorbed together with only some of the C02- The spent liquor from the second absorber is stripped in a second regenerator and then contains the desired high amount of H2S. Such a system is proposed for instance by Dow Chemical Cie. for their Selectamin Process [2.18]. 

After cooling, the gas enters the amine absorber where essentially all of the hydrogen sulfide is removed, but only a portion of the carbon dioxide is coab.sorbed. The rich amine solution is stripped of acid gas in the regenerator by application of indirect heat supplied by a steam heated rehoiler, and the acid gas is returned to the Claus unit. This portion of the process is quite similar to the conventional selective ethanolamine processes discussed in Chapter 2. 

The Resulf process, which is licensed by TPA, Inc., is very similar to the BSR/MDEA, SCOT, and Sulften processes. The Claus plant tail gas is heated mixed with a reducing gas passed through a catalyst bed where sulfur vapor, SO2, COS. and CS2 ate converted to H2S cooled and passed through a selective amine absorber. Acid gas from the amine stripper is recycled to the Claus plant. It is claimed that a high efficiency version of the process, Resulf-10, produces a vent gas from the amine absorber containing a maximum of 10 ppm H2S (TPA Inc., 1994). 

Clause 6.2.1 requires that The Safety Instrumented Systems (SIS) architecture for each safety function shall be selected to meet its required Safety Integrity Level (SIL). (e.g. the selected architecture may be one out of one lool, loo2 voting, 2oo3 voting, etc.) This is an important feature and is one that has become a significant feature of the lEC standards 61508 and 61511 where the architecture of each part or subsystem of the SIS must comply with certain minimum requirements for fault tolerance. We shall examine these in more detail in Chapter 7... 

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