cannot specify a name for a column check constraint

<column constraint definition> ::=

[ <constraint name definition> ] <column constraint> [ <constraint characteristics> ]

<column constraint> ::=

...

| <check constraint definition>

<constraint name definition> ::=

CONSTRAINT <constraint name>

<check constraint definition> ::=

CHECK <left paren> <search condition> <right paren>

create table t1 (a int constraint foo check (a > 5));