Query operators in CONSTRUCT

The CONSTRUCT instruction supports a specific query syntax, using wildcard characters and comparison operators.

The table below lists CONSTRUCT wildcard characters that can be used during a query by example input:

Table 1. CONSTRUCT relational operators
Symbol	Meaning	Data type
value	Use value as is to filter	Any simple type
`=`	Is NULL	Any simple type
`==`	Equal to	Any simple type
`>`	Greater than	Any simple type
`>=`	Greater than or equal to	Any simple type
`<`	Less than	Any simple type
`<=`	Less than or equal to	Any simple type
`<>` or `!=`	Not equal to	Any simple type
`!=`	Not NULL	Any simple type
`: or ..`	Range of values	Any simple type
`\|`	List of values	Any simple type
`*`	Wildcard for any string	Char string types
`?`	Single-character wildcard	Char string types
`[c1-c2]`	Range of characters	Char string types
`[c1c2...]`	Set of characters	Char string types

Queries based on character types are case sensitive, because SQL is case sensitive, except if the database server is configured to be case-insensitive.

The * (star) and ? (question mark) wildcards are specific to character string type queries, and will generate a MATCHES expression or a LIKE expression, according to the type of database used. When entering a * or ?, the pattern can also contain a character range specification with the square brackets notation [a-z] or [xyz]. A caret ( ^. ) as the first character within the square brackets specifies the logical complement of the set, and matches any character that is not listed. For example, the search value [^AB]* specifies all strings beginning with characters other than A or B.

Some syntaxes can produce an Error in field dialog error if the feature is supported by the pattern matching operator of the database server. For example, not all db servers support the [a-z] character range specification in the LIKE pattern.

If you want to search for rows with values containing a * star, a ? question mark or a \ backslash, you must escape the wildcard character with a backslash. Specifying a backslash before another character will have no effect.

Table 2. CONSTRUCT input examples with matching and non matching values
QBE input example	Matching values	Non matching values
100	100	99, 101, NULL
>=100	100, 101, 200	10, 99, NULL
!=100	98, 98, 101, 102	100, NULL
!=	98, 99, 100, 101	NULL
1:100	1, 2 ... 99, 100	0, 101, NULL
aaa:yyy	aaa, aab, ab, yy, yyy	zaa, NULL
abc	abc	bc, abcd, Abc, NULL
ABC	ABC	abc, aBC, NULL
abc*	abc, abcd, abcdef	bc, ABC, NULL
*bc	abc, bc	acd, aBC, NULL
?bc	abc, xbc, zbc	aabc, aBC, NULL
*bc?	aaaabc, abcd, bcd	abcdef, bcdef, NULL
[a-z]bc	abc, ebc, zbc	2bc, +bc, Abc, NULL
[^abc]*	deee, feee, zyx, z	azzz, byy, d, NULL
a[bxy]c	abc, axc, ayc	a2c, azc, aBc, NULL
*[xyz]	abcx, eeeez	abcd, eeee, NULL
1\|2\|35	1, 2, 35	4, 5, 6, NULL
aa\|bb\|cc	aa, bb, cc	ab, dd, NULL
\\abc*	\abc, \abcdef	abc, NULL
\*bc	*bc	abc, bc, NULL
\[?\]	[a], a[b]c, xx[y]zz	a[bb]c, a[]c, NULL