Syntax rules for search filters

1. The first line contains always the text <select where>. This formulation was based on SQL.
2. The second line always begins with a left parenthesis.
3. The further lines contain a filter instruction or a parenthesis.
4. The last line contains the right parenthesis.

Logical operators for filter instructions

AND: The filter instruction of this line is AND combined with the preceding one.

OR: The filter instruction of this line is OR combined with the preceding one.

Compare operators <, >, =, <> and compare values

Upper-case / lower-case are ignored!
<, > Number: Numeric compare of field contents and number.
<, > ’Text’: Text compare of field contents and number.
= Number: Test if equal. (Numeric compare)
= ’Text’: Test if equal. (Text compare)
= ’*Text’: Test whether the field content contains 'text'.
= ’Text*’: Test whether the field content begins with 'text'.
<> ’Text’: Test whether the field contents is different from 'text'.
<> Number: Test whether the field content is different from Number.

Filter Instruction (line)

Example with two lines

<font face="Courier New">select where
(
    City = 'Berlin'
    AND Firm = '*Inc'
)

• The first filter instruction to a left parenthesis begins with a field name. All further filter instructions within the same parenthesis level begin with a logical operator (AND/OR), followed from a field name.
• After the field name comes a blank, then a compare operator, then again a blank followed from the compare value.

Example with sub-parenthesis

<font face="Courier New">select where
(
    City = 'Berlin'
    AND (
            Firm = '*Inc'
            OR Firm = '* AG.'
        )
)

• Subordinate clip tiers can be inserted by hand. You always begin with a logical operator (AND/OR), followed from a left parenthesis and a line wrap. (Behind a left parenthesis no further instructions must stand in the same line.)
• The following lines contain in each case a filter instruction.
• The left parenthesis is to be locked through a left parenthesis in a separate line.
• In order to increase the readability, the clip tiers should be indented as in the example. Blanks or tabulators can be used for that.