Step 5. Write an Expression

There are three basic questions you can ask the Query engine.

1	What are the values of all the attributes for an item in the same order you asked for them?
2	Does an item meet the expression criteria?
3	What items of a specified type match the expression?

Operators include:

Comparison Operators
For TADB attributes
=	Logical EQUALS operator.
<	Logical LESS THAN operator.
>	Logical GREATER THAN operator.
<=	Logical LESS THAN or EQUALS operator.
>=	Logical GREATER THAN or EQUALS operator.
=l	Logical SQL LIKE operator. Note: The appropriate information about acceptable wild cards and pattern matching characters can be found in SQL Server Books Online: Access the index. Select the entry called LIKE comparisons. Select the entry called LIKE Transact-SQL Reference.
=r	Logical regular expression comparison operator.
For non-TADB attributes
=	Logical EQUALS operator.
=r	Logical regular expression comparison operator.
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Boolean Operators
!	Logical NOT operator (placed before an expression)
&	Logical AND operator.
\|	Logical OR operator
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Other Syntax Tools
( )	To group expression elements.
' '	To identify literal values
,	To form sub-string expressions.
.	To identify attributes
$$	To identify references to named expressions.
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Note: There is no Not Comparison Operator. When an expression should be a not expression, a ! is placed before the expression.

Order Execution Mgt. Query configuration.