Difference between revisions of "Using Logical Operators and Parentheses"

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Boolean operators are used to build subexpressions within an expression, resulting in the ability to create multiple conditions and complex criteria.
Logical operators combine subexpressions into a larger expression, to specify multiple conditions and complex criteria.


<tt><subexpression1> <Boolean_operator> <subexpression2>...</tt>
: <tt><subexpression1> <Logical_operator> <subexpression2>...</tt>


{{:Boolean}}
{{:Boolean}}


Use parentheses (brackets) to group expressions logically and to join one or more expressions. Parentheses are used in pairs. For each left parenthesis, there must be a right parenthesis.
===Precedence ===


:<tt>((<subexpression_1> && <subexpression_2>) || <subexpression_3>) && (<subexpression_4)</tt>
Expressions are evaluated in this order:
#expressions within <tt>(parentheses)</tt> Β 
#expressions with Logical <tt>AND</tt> Β 
#expressions with Logical <tt>OR</tt>


===Precedence ===
::''If the expression is not clearly annotated with parentheses, then Logical <tt>AND</tt> takes precedence over Logical <tt>OR</tt>''


Expressions are evaluated in this order:
{{Tip|For any complex expression, always use parentheses. That way, you're sure to get what you expect, and the meaning is clear when you or anyone else reads it later.}}
#expressions within <tt>(parenthesis)</tt>
#expressions with <tt>&& (Logical AND)</tt>
#expressions with <tt>|| (Logical OR)</tt>


::''If the expression is not clearly annotated with parentheses, then <tt>&&</tt> (Logical AND) takes precedence over <tt>||</tt> (Logical OR)''
===Examples===


{| border="1" cellpadding="5" cellspacing="0"
:*Find all accounts where the state is either California, Nevada, or Washington
!Expression
::<tt><nowiki>(State = 'CA') OR (State = 'NV') OR (State = 'WA')</nowiki></tt>
!Description
:*Find all accounts where the state is not California, Nevada, or Washington:
|-
::<tt><nowiki>(State != 'CA') AND (State != 'NV') AND (State != 'WA')</nowiki></tt>
|<tt><nowiki>(Number of Employees <50 && Area_Code = '408') || (State = 'CA' && Industry = 'Construction'</nowiki></tt>||This expression finds all accounts that have fewer than 50 employees located in area code 408 or accounts in the construction industry in California
:*Find all accounts in the construction industry where the state is California or Nevada
|-
::<tt><nowiki>((State = 'CA') OR (State = 'NV')) AND (Industry = 'Construction')</nowiki></tt>
|<tt><nowiki>(State = 'CA') || (State = 'NV') || (State = 'WA')</nowiki></tt>||This expression finds all accounts where the state is either California, Nevada, or Washington
:*Finds account in the State of California or accounts in construction in the state of Nevada
|-
::<tt><nowiki>State = 'CA' OR State = 'NV' AND Industry = 'Construction'</nowiki></tt>
|<tt><nowiki>(State != 'CA') && (State != 'NV') && (State != 'WA')</nowiki></tt>||By contrast, this expression finds all accounts where the state is not California, Nevada, or Washington
:*Also finds account in the State of California or accounts in construction in the state of Nevada (the <tt>AND (AND)</tt> operator implies brackets)
|-
::<tt><nowiki>State = 'CA' OR (State = 'NV' AND Industry = 'Construction')</nowiki></tt>
|<tt><nowiki>((State = 'CA') || (State = 'NV')) && (Industry = 'Construction')</nowiki></tt>||This expression finds all accounts in the construction industry where the state is California or Nevada
:*Find accounts in California or Texas where the account name contains "Equipment"
|-
::<tt><nowiki>(Acct_Name contains 'Equipment') AND (state = 'CA' OR state ='TX')</nowiki></tt>
|<tt><nowiki>State = 'CA' || State = 'NV' && Industry = 'Construction'</nowiki></tt>||Taking the example from above, but removing the parentheses finds accounts in the State of California or accounts in construction in the state of Nevada
:*Find accounts in California where the account name contains "Equipment", or any record in Texas
|-
::<tt><nowiki>(Acct_Name contains 'Equipment') AND (state = 'CA')) OR (state ='TX')</nowiki></tt>
|<tt><nowiki>State = 'CA' || (State = 'NV' && Industry = 'Construction')</nowiki></tt>||Note that the <tt>AND (&&)</tt> operator implies parentheses
|-
|<tt><nowiki>contains(Acct_Name, 'Equipment') && (state = 'CA' || state ='TX')</nowiki></tt>||This expression finds accounts in California or Texas where the account name contains "Equipment"
|-
|<tt><nowiki>contains(Acct_Name, 'Equipment') && (state = 'CA') || state ='TX'</nowiki></tt>||This expression finds accounts in California where the account name contains "Equipment", or any record in Texas.
|}

Latest revision as of 17:45, 13 June 2011

Logical operators combine subexpressions into a larger expression, to specify multiple conditions and complex criteria.

<subexpression1> <Logical_operator> <subexpression2>...

LOGICAL_OPERATOR

Logical operators can be used to build more complex expressions.
The logical operators are:
AND
OR
Considerations
  • Two subexpressions joined by a logical operator form a logical expression.
  • Logical expressions resolve to a Boolean value: 1/0 or TRUE/FALSE.
  • Use parentheses--()--to group expressions logically and to join multiple expressions.
  • Parentheses are used in pairs; each open parenthesis "(" requires a closing parenthesis ")".
  • For example:
((<expression1> AND <expression2>) OR (<expression3> AND <expression_4>))


Precedence

Expressions are evaluated in this order:

  1. expressions within (parentheses)
  2. expressions with Logical AND
  3. expressions with Logical OR
If the expression is not clearly annotated with parentheses, then Logical AND takes precedence over Logical OR

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Tip: For any complex expression, always use parentheses. That way, you're sure to get what you expect, and the meaning is clear when you or anyone else reads it later.

Examples

  • Find all accounts where the state is either California, Nevada, or Washington
(State = 'CA') OR (State = 'NV') OR (State = 'WA')
  • Find all accounts where the state is not California, Nevada, or Washington:
(State != 'CA') AND (State != 'NV') AND (State != 'WA')
  • Find all accounts in the construction industry where the state is California or Nevada
((State = 'CA') OR (State = 'NV')) AND (Industry = 'Construction')
  • Finds account in the State of California or accounts in construction in the state of Nevada
State = 'CA' OR State = 'NV' AND Industry = 'Construction'
  • Also finds account in the State of California or accounts in construction in the state of Nevada (the AND (AND) operator implies brackets)
State = 'CA' OR (State = 'NV' AND Industry = 'Construction')
  • Find accounts in California or Texas where the account name contains "Equipment"
(Acct_Name contains 'Equipment') AND (state = 'CA' OR state ='TX')
  • Find accounts in California where the account name contains "Equipment", or any record in Texas
(Acct_Name contains 'Equipment') AND (state = 'CA')) OR (state ='TX')