CREATE TABLE [my_table] (
  [id] INTEGER NOT NULL  
, [r_type] NVARCHAR(1) NOT NULL CHECK (r_type IN ('A','P','S')) DEFAULT ('S') -- RESOURCE TYPE Array, Plural, Single
, [symbol] NVARCHAR(50) NOT NULL
, [default_text] NVARCHAR(4000)
, CHECK ((r_type = 'S' AND default_text IS NOT NULL) OR (r_type IN ('A', 'P')))
, CONSTRAINT [PK_Keys] PRIMARY KEY ([id])
, CONSTRAINT [UK1_Keys] UNIQUE ([symbol])
);