Support : Dialog Search Aids : Successful Searching : SELECT : Order of Processing

SELECT (continued)

Search Terms (continued)

Multiple-Term SELECT Statements

When you want to enter more than one search term in a SELECT statement, insert logical or proximity operators between the individual terms. You can enter up to 240 characters, including spacing and punctuation, in a single SELECT statement.

SELECT lists each term in the intermediate results, along with the number of records in which it was found, and produces a single, final set. SELECT STEPS produces a set for each term and proximity operation in the SELECT statement, plus a final, combining set.

Note: SELECT STEPS allows maximum flexibility in searching, since it produces individual sets that can be used in place of the terms they represent. However, SELECT may produce faster processing than SELECT STEPS in long searches in large files. SELECT is also recommended when using SELECT STEPS might create more sets than the maximum 400 allowed.

• To use SELECT STEPS for flexibility in modifying your search:

File 6:NTIS 1964-2007/Nov W4 
(c) 2007 NTIS, Intl Cpyrght All Rights Res
 
      Set  Items  Description
      ---  -----  -----------
?ss ozone or chlorofluorcarbon? or cfc?
      S1    8656  OZONE
      S2       8  CHLOROFLUORCARBON?
      S3    1117  CFC?
      S4    9446  OZONE OR CHLOROFLUORCARBON? OR CFC?
?ss warming or greenhouse(w)effect
      S5    1755  WARMING
      S6    3893  GREENHOUSE
      S7  140800  EFFECT
      S8    1938  GREENHOUSE(W)EFFECT
      S9    3133  WARMING OR GREENHOUSE(W)EFFECT
?s s4 and s9
           9446  S4
            3133  S9
     S10     469  S4 AND S9
?ss global(w)s5
     S11   25131  GLOBAL
            1755  S5
     S12     802  GLOBAL(W)S5
?s s4 and (s8 or s12)
            9446  S4
            1938  S8
             802  S12
     S13     440  S4 AND (S8 OR S12)

Logical and Proximity Operators
Three kinds of logical relationships can be defined on Dialog: OR, AND, and NOT. OR logic is specified using the word OR, truncation, or range searching. AND logic is specified using the word AND or a proximity operator. NOT logic is specified using the word NOT or a NOT proximity operator.

You can use any of the logical operators (OR, AND, and NOT) and any of the proximity operators in the same SELECT statement. When you use two or more different operators in a SELECT statement, you must be sure that the statement will be processed correctly. When necessary, use parentheses to specify the order of processing of the statement.

(Order of Processing) 

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