Using &NDBSCAN Statements › Scan Expressions › CONTAINS

CONTAINS

The CONTAINS operator is extremely useful when scanning text in a database. When combined with generic or range field names, a single expression can perform quite sophisticated lookups.

Some notes about the use of CONTAINS:

• CONTAINS involves scanning records. Always try to have other criteria ANDed with CONTAINS, to reduce the number of records that must be scanned.
• The field(s) on the left of CONTAINS are padded at each end with one blank, for the purposes of searching. This allows words to be searched for, by providing blanks around your search arguments, without worrying that a word at the front or back of a field will not be matched. For example, a field value of A SENTENCE OF WORDS is regarded as A SENTENCE OF WORDS when processed by CONTAINS. Thus, searching for the value A will succeed, even though the data does not contain a blank in front of the A.
• The ANY and ALL keywords allow some requirements for text to be adjacent to be tested. For example the following statement only matches records where any one of the fields prefixed by DESC contains both WORD1 and WORD2:

  ANY FIELD DESC* CONTAINS ALL WORD1, WORD2.
  

  If each DESC... field held a sentence, this is equivalent to asking for a sentence containing both words.

  Fields in the same record can contain the search argument(s). Thus, it is possible to find all records where a given character field in the records is contained within another character field.