DbError = object of IOError

SqlQuery = distinct string

DbEffect = object of IOEffect

ReadDbEffect = object of DbEffect

WriteDbEffect = object of DbEffect

DbTypeKind = enum
  dbUnknown,                  ## unknown datatype
  dbSerial,                   ## datatype used for primary auto-increment keys
  dbNull,                     ## datatype used for the NULL value
  dbBit,                      ## bit datatype
  dbBool,                     ## boolean datatype
  dbBlob,                     ## blob datatype
  dbFixedChar,                ## string of fixed length
  dbVarchar,                  ## string datatype
  dbJson,                     ## JSON datatype
  dbXml,                      ## XML datatype
  dbInt,                      ## some integer type
  dbUInt,                     ## some unsigned integer type
  dbDecimal,                  ## decimal numbers (fixed-point number)
  dbFloat,                    ## some floating point type
  dbDate,                     ## a year-month-day description
  dbTime,                     ## HH:MM:SS information
  dbDatetime,                 ## year-month-day and HH:MM:SS information,
             ## plus optional time or timezone information
  dbTimestamp, ## Timestamp values are stored as the number of seconds
              ## since the epoch ('1970-01-01 00:00:00' UTC).
  dbTimeInterval,             ## an interval [a,b] of times
  dbEnum,                     ## some enum
  dbSet,                      ## set of enum values
  dbArray,                    ## an array of values
  dbComposite,                ## composite type (record, struct, etc)
  dbUrl,                      ## a URL
  dbUuid,                     ## a UUID
  dbInet,                     ## an IP address
  dbMacAddress,               ## a MAC address
  dbGeometry,                 ## some geometric type
  dbPoint,                    ## Point on a plane   (x,y)
  dbLine,                     ## Infinite line ((x1,y1),(x2,y2))
  dbLseg,                     ## Finite line segment   ((x1,y1),(x2,y2))
  dbBox,                      ## Rectangular box   ((x1,y1),(x2,y2))
  dbPath,                     ## Closed or open path (similar to polygon) ((x1,y1),...)
  dbPolygon,                  ## Polygon (similar to closed path)   ((x1,y1),...)
  dbCircle,                   ## Circle   <(x,y),r> (center point and radius)
  dbUser1,                    ## user definable datatype 1 (for unknown extensions)
  dbUser2,                    ## user definable datatype 2 (for unknown extensions)
  dbUser3,                    ## user definable datatype 3 (for unknown extensions)
  dbUser4,                    ## user definable datatype 4 (for unknown extensions)
  dbUser5                     ## user definable datatype 5 (for unknown extensions)

DbType = object
  kind*: DbTypeKind            ## the kind of the described type
  notNull*: bool               ## does the type contain NULL?
  name*: string                ## the name of the type
  size*: Natural               ## the size of the datatype; 0 if of variable size
  maxReprLen*: Natural         ## maximal length required for the representation
  precision*, scale*: Natural   ## precision and scale of the number
  min*, max*: BiggestInt        ## the minimum and maximum of allowed values
  validValues*: seq[string]    ## valid values of an enum or a set
  

DbColumn = object
  name*: string                ## name of the column
  tableName*: string           ## name of the table the column belongs to (optional)
  typ*: DbType                 ## type of the column
  primaryKey*: bool            ## is this a primary key?
  foreignKey*: bool            ## is this a foreign key?
  

DbColumns = seq[DbColumn]

proc dbError(msg: string) {...}{.noreturn, noinline, raises: [DbError], tags: [].}

template sql(query: string): SqlQuery