Entries in type char[] (1)

How do I declare a table column of type string (not symbol!)?

Declare it without a type as follows:

q)t: ([] str: ())
q)meta t
c  | t f a
---| -----
str|      
q)

A the type of a column defined as () is determined when the first row is inserted:

q)`t insert enlist enlist "foo"
,0
q)t
str  
-----
"foo"
q)meta t
c  | t f a
---| -----
str| C    
q)

Beware: if the column is emptied, it loses its type. See this related faq.