Database.PostgreSQL.Describe

Utility function for describing a table in the database.

Documentation

data ColumnInfo

Constructors

ColumnInfo

Fields

• colNum :: !Int16

  Internal column number used by PostgreSQL. Generally these will be consecutive starting from 1, but this may not be the case if you have altered a table to delete columns.

• colName :: ByteString

  Name of the column

• colType :: !TypeInfo

  Type of the column

• colNotNull :: !Bool

  If True, the database cannot contain null. (This constraint should always be accurate.)

• colPrimary :: !Bool

  True if this column (and only this column) constitutes the primary key of the table. Always False if the primary key comprises multiple columns (even if this is one of those columns).

• colUnique :: !Bool

  True if there is a uniqueness constraint on this column. Not True if this column is part of a uniqueness constraint involving multiple columns. (Such multi-column uniqueness constraints are not reported by this interface.)

• colReferences :: !(Maybe ByteString)

  If this there is a foreign key constraint on this column (and the constraint does not span multiple columns), report the table referenced by this column.

Instances

Show ColumnInfo

Methods

showsPrec :: Int -> ColumnInfo -> ShowS

show :: ColumnInfo -> String

showList :: [ColumnInfo] -> ShowS

describeTable :: Connection -> ByteString -> IO [ColumnInfo]

Returns a list of ColumnInfo structures for a particular table. Not all information about a table is returned. In particular, constraints that span columns are ignored.