MATCHES and LIKE

Informix®

Informix supports MATCHES and LIKE operators in SQL statements.

MATCHES expects * and ? wild-card characters, while LIKE uses the % and _ wild-cards as equivalents.

( col MATCHES 'Smi*' AND col NOT MATCHES 'R?x' )
( col LIKE 'Smi%' AND col NOT LIKE 'R_x' )

MATCHES accepts also brackets notation, to specify a set of matching characters at a given position:

( col MATCHES '[Pp]aris' )
( col MATCHES '[0-9][a-z]*' )

IBM® DB2®

IBM DB2 does not provide an equivalent of the Informix MATCHES operator.

The LIKE operator is supported.

Important:

With IBM DB2 , columns defined as CHAR(N) are blank padded, and trailing blanks are significant in the LIKE expressions. As result, with a CHAR(5) value such as 'abc ' (with 2 trailing blanks), the expression (colname LIKE 'ab_') will not match. To workaround this behavior, you can do (RTRIM(colname) LIKE 'pattern'). However, consider adding the condition AND (colname LIKE 'patten%') to force the DB server to optimize the query of the column is indexed. The CONSTRUCT instruction uses this technique when the entered criteria does not end with a * star wildcard.

Solution

The database driver is able to translate Informix MATCHES expressions to LIKE expressions, when no [ ] bracket character ranges are used in the MATCHES operand.

The MATCHES to LIKE expression translation is controlled by the following FGLPROFILE entry:

dbi.database.dbname.ifxemul.matches = { true | false }

Important:

Only [NOT] MATCHES followed by a search pattern provided as a string literal can be converted by ODI drivers. A [NOT] MATCHES followed by a ? question mark parameter place holder is not translated!

For maximum portability, consider replacing the MATCHES expressions with LIKE expressions in all SQL statements.

Avoid using CHAR(N) types for variable length character data (such as name, address).