I'm facing a problem I have seen before but never got the time to report until now that is biting me again. I have a table which has some CHECK constrains using regular expressions and one check is failing when I try to insert some valid data. The constraint definition is: «nombre propio válido» CHECK (nombre ~ '^[[:upper:]][[:lower:]]*([-\'. [:alpha:]]+)?$'::text) And the data is ``José Luis''. Using a SELECT with the expression and the data leads true as expected: masm=# select 'José Luis' ~ '^[[:upper:]][[:lower:]]*([-\'. [:alpha:]]+)?$'; ?column? ---------- t (1 fila) However when I try to insert one tuple using the same data it fails: masm=# INSERT INTO persona.persona (nombre, fecha_nacimiento, sexo) VALUES ('José Luis', CAST('1979-06-15' AS date), 'm'); ERROR: el nuevo registro para la relación «persona» viola la restricción check «nombre propio válido» Wired. A workaround that used to work was to put the select statement and then the insert: select 'José Luis' ~ '^[[:upper:]][[:lower:]]*([-\'. [:alpha:]]+)?$'; INSERT INTO persona.persona (nombre, fecha_nacimiento, sexo) VALUES ('José Luis', CAST('1979-06-15' AS date), 'm'); but it doesn't any more :-(. Btw, this is PostgreSQL 8.0.4, running on Fedora Core 4. Best Regards, Manuel.