Database.HDBC.Types

HDBC-2.4.0.2: Haskell Database Connectivity

Copyright | Copyright (C) 2005-2011 John Goerzen
License | BSD3
Maintainer | John Goerzen <jgoerzen@complete.org>
Stability | provisional
Portability | portable
Safe Haskell | Safe
Language | Haskell98

Database.HDBC.Types

Description

Types for HDBC.

Please note: this module is intended for authors of database driver libraries only. Authors of applications using HDBC should use `HDBC` exclusively.

Written by John Goerzen, jgoerzen@complete.org

Synopsis

- class IConnection conn where
- data Statement = Statement {
  - execute :: [SqlValue] -> IO Integer
  - executeRaw :: IO ()
  - executeMany :: [[SqlValue]] -> IO ()
  - finish :: IO ()
  - fetchRow :: IO (Maybe [SqlValue])
  - getColumnNames :: IO [String]
  - originalQuery :: String
  - describeResult :: IO [(String, SqlColDesc)]
  }
- data SqlError = SqlError {
  - seState :: String
  - seNativeError :: Int
  - seErrorMsg :: String
  }
- nToSql :: Integral a => a -> SqlValue
- iToSql :: Int -> SqlValue
- posixToSql :: POSIXTime -> SqlValue
- fromSql :: Convertible SqlValue a => SqlValue -> a
- safeFromSql :: Convertible SqlValue a => SqlValue -> ConvertResult a
- toSql :: Convertible a SqlValue => a -> SqlValue
- data SqlValue
  - = SqlString String
  - | SqlByteString ByteString
  - | SqlWord32 Word32
  - | SqlWord64 Word64
  - | SqlInt32 Int32
  - | SqlInt64 Int64
  - | SqlInteger Integer
  - | SqlChar Char
  - | SqlBool Bool
  - | SqlDouble Double
  - | SqlRational Rational
  - | SqlLocalDate Day
  - | SqlLocalTimeOfDay TimeOfDay
  - | SqlZonedLocalTimeOfDay TimeOfDay TimeZone
  - | SqlLocalTime LocalTime
  - | SqlZonedTime ZonedTime
  - | SqlUTCTime UTCTime
  - | SqlDiffTime NominalDiffTime
  - | SqlPOSIXTime POSIXTime
  - | SqlEpochTime Integer
  - | SqlTimeDiff Integer
  - | SqlNull
- data ConnWrapper = IConnection conn => ConnWrapper conn
- withWConn :: forall b. ConnWrapper -> (forall conn. IConnection conn => conn -> b) -> b

# Documentation

class IConnection conn where #

Main database handle object.

An `IConnection` object is created by specific functions in the module for an individual database. That is, the connect function -- which creates this object -- is not standardized through the HDBC interface.

A connection is closed by a call to `disconnect`.

A call to `commit` is required to make sure that your changes get committed to the database. In other words, HDBC has no support for autocommit, which we consider an outdated notion.

Minimal complete definition

disconnect, commit, rollback, run, prepare, clone, hdbcDriverName, hdbcClientVer, proxiedClientName, proxiedClientVer, dbServerVer, dbTransactionSupport, getTables, describeTable

Methods

disconnect :: conn -> IO () #

Disconnect from the remote database.

You do not need to explicitly close an IConnection object, but you may do so if you so desire. If you don't, the object will disconnect from the database in a sane way when it is garbage-collected. However, a disconnection may raise an error, so you are encouraged to explicitly call `disconnect`. Also, garbage collection may not run when the program terminates, and some databases really like an explicit disconnect.

So, bottom line is, you're best off calling `disconnect` directly, but the world won't end if you forget.

This function discards any data not committed already. Database driver implementators should explicitly call `rollback` if their databases don't do this automatically on disconnect.

Bad Things (TM) could happen if you call this while you have `Statement`s active. In more precise language, the results in such situations are undefined and vary by database. So don't do it.

commit :: conn -> IO () #

Commit any pending data to the database.

Required to make any changes take effect.

rollback :: conn -> IO () #

Roll back to the state the database was in prior to the last `commit` or `rollback`.

runRaw :: conn -> String -> IO () #

Execute an SQL string, which may contain multiple queries. This is intended for situations where you need to run DML or DDL queries and aren't interested in results.

run :: conn -> String -> [SqlValue] -> IO Integer #

Execute a single SQL query. Returns the number of rows modified (see `execute` for details). The second parameter is a list of replacement values, if any.

prepare :: conn -> String -> IO Statement #

Prepares a statement for execution.

Question marks in the statement will be replaced by positional parameters in a later call to `execute`.

Please note that, depending on the database and the driver, errors in your SQL may be raised either here or by `execute`. Make sure you handle exceptions both places if necessary.

clone :: conn -> IO conn #

Create a new `Connection` object, pointed at the same server as this object is. This will generally establish a separate physical connection.

When you wish to establish multiple connections to a single server, the correct way to do so is to establish the first connection with the driver-specific connection function, and then clone it for each additional connection.

This can be important when a database doesn't provide much thread support itself, and the HDBC driver module must serialize access to a particular database.

This can also be a handy utility function whenever you need a separate connection to whatever database you are connected to already.

hdbcDriverName :: conn -> String #

The name of the HDBC driver module for this connection. Ideally would be the same as the database name portion of the Cabal package name. For instance, "sqlite3" or "odbc". This is the layer that is bound most tightly to HDBC.

hdbcClientVer :: conn -> String #

The version of the C (or whatever) client library that the HDBC driver module is bound to. The meaning of this is driver-specific. For an ODBC or similar proxying driver, this should be the version of the ODBC library, not the eventual DB client driver.

proxiedClientName :: conn -> String #

In the case of a system such as ODBC, the name of the database client/server in use, if available. For others, identical to `hdbcDriverName`.

proxiedClientVer :: conn -> String #

In the case of a system such as ODBC, the version of the database client in use, if available. For others, identical to `hdbcClientVer`. This is the next layer out past the HDBC driver.

dbServerVer :: conn -> String #

The version of the database server, if available.

dbTransactionSupport :: conn -> Bool #

Whether or not the current database supports transactions. If False, then `commit` and `rollback` should be expected to raise errors.

MySQL is the only commonly-used database that is known to not support transactions entirely. Please see the MySQL notes in the ODBC driver for more information.

getTables :: conn -> IO [String] #

The names of all tables accessible by the current connection, excluding special meta-tables (system tables).

You should expect this to be returned in the same manner as a result from `fetchAllRows'`.

All results should be converted to lowercase for you before you see them.

describeTable :: conn -> String -> IO [(String, SqlColDesc)] #

Obtain information about the columns in a specific table. The String in the result set is the column name.

You should expect this to be returned in the same manner as a result from `fetchAllRows'`.

All results should be converted to lowercase for you before you see them.

Instances

IConnection ConnWrapper # |
Methods disconnect :: ConnWrapper -> IO () # commit :: ConnWrapper -> IO () # rollback :: ConnWrapper -> IO () # runRaw :: ConnWrapper -> String -> IO () # run :: ConnWrapper -> String -> [SqlValue] -> IO Integer # prepare :: ConnWrapper -> String -> IO Statement # clone :: ConnWrapper -> IO ConnWrapper # hdbcDriverName :: ConnWrapper -> String # hdbcClientVer :: ConnWrapper -> String # proxiedClientName :: ConnWrapper -> String # proxiedClientVer :: ConnWrapper -> String # dbServerVer :: ConnWrapper -> String # dbTransactionSupport :: ConnWrapper -> Bool # getTables :: ConnWrapper -> IO [String] # describeTable :: ConnWrapper -> String -> IO [(String, SqlColDesc)] #

data Statement #

Constructors

Statement |
Fields execute :: [SqlValue] -> IO Integer Execute the prepared statement, passing in the given positional parameters (that should take the place of the question marks in the call to `prepare`). For non-SELECT queries, the return value is the number of rows modified, if known. If no rows were modified, you get 0. If the value is unknown, you get -1. All current HDBC drivers support this function and should never return -1. For SELECT queries, you will always get 0. This function should automatically call finish() to finish the previous execution, if necessary. executeRaw :: IO () Execute the statement as-is, without supplying any positional parameters. This is intended for statements for which the results aren't interesting or present (e.g., DDL or DML commands). If your query contains placeholders, this will certainly fail; use `execute` instead. executeMany :: [[SqlValue]] -> IO () Execute the query with many rows. The return value is the return value from the final row as if you had called `execute` on it. Due to optimizations that are possible due to different databases and driver designs, this can often be significantly faster than using `execute` multiple times since queries need to be compiled only once. This is most useful for non-SELECT statements. finish :: IO () Abort a query in progress -- usually not needed. fetchRow :: IO (Maybe [SqlValue]) Fetches one row from the DB. Returns `Nothing` if there are no more rows. Will automatically call `finish` when the last row is read. getColumnNames :: IO [String] Returns a list of the column names in the result. For maximum portability, you should not assume that information is available until after an `execute` function has been run. Information is returned here directly as returned by the underlying database layer. Note that different databases have different rules about capitalization of return values and about representation of names of columns that are not simple columns. For this reason, it is suggested that you treat this information for display purposes only. Failing that, you should convert to lower (or upper) case, and use `AS` clauses for anything other than simple columns. A simple getColumnNames implementation could simply apply `map fst` to the return value of `describeResult`. originalQuery :: String The original query that this `Statement` was prepared with. describeResult :: IO [(String, SqlColDesc)] Obtain information about the columns in the result set. Must be run only after `execute`. The String in the result set is the column name. You should expect this to be returned in the same manner as a result from `fetchAllRows'`. All results should be converted to lowercase for you before you see them. Please see caveats under `getColumnNames` for information on the column name field here.

data SqlError #

The main HDBC exception object. As much information as possible is passed from the database through to the application through this object.

Errors generated in the Haskell layer will have seNativeError set to -1.

Constructors

SqlError |
Fields seState :: String seNativeError :: Int seErrorMsg :: String

Instances

Eq SqlError # |
Methods (==) :: SqlError -> SqlError -> Bool # (/=) :: SqlError -> SqlError -> Bool #
Read SqlError # |
Methods readsPrec :: Int -> ReadS SqlError # readList :: ReadS [SqlError] # readPrec :: ReadPrec SqlError # readListPrec :: ReadPrec [SqlError] #
Show SqlError # |
Methods showsPrec :: Int -> SqlError -> ShowS # show :: SqlError -> String # showList :: [SqlError] -> ShowS #
Exception SqlError # |
Methods toException :: SqlError -> SomeException # fromException :: SomeException -> Maybe SqlError # displayException :: SqlError -> String #

nToSql :: Integral a => a -> SqlValue #

Converts any Integral type to a `SqlValue` by using toInteger.

iToSql :: Int -> SqlValue #

Convenience function for using numeric literals in your program.

posixToSql :: POSIXTime -> SqlValue #

Convenience function for converting `POSIXTime` to a `SqlValue`, because `toSql` cannot do the correct thing in this instance.

fromSql :: Convertible SqlValue a => SqlValue -> a #

Convert from an `SqlValue` to a Haskell value. Any problem is indicated by calling `error`. This function is simply a restricted-type wrapper around `convert`. See extended notes on `SqlValue`.

safeFromSql :: Convertible SqlValue a => SqlValue -> ConvertResult a #

Conversions to and from `SqlValue`s and standard Haskell types.

This function converts from an `SqlValue` to a Haskell value. Many people will use the simpler `fromSql` instead. This function is simply a restricted-type wrapper around `safeConvert`.

toSql :: Convertible a SqlValue => a -> SqlValue #

Convert a value to an `SqlValue`. This function is simply a restricted-type wrapper around `convert`. See extended notes on `SqlValue`.

data SqlValue #

`SqlValue` is the main type for expressing Haskell values to SQL databases.

INTRODUCTION TO SQLVALUE

This type is used to marshall Haskell data to and from database APIs. HDBC driver interfaces will do their best to use the most accurate and efficient way to send a particular value to the database server.

Values read back from the server are constructed with the most appropriate `SqlValue` constructor. `fromSql` or `safeFromSql` can then be used to convert them into whatever type is needed locally in Haskell.

Most people will use `toSql` and `fromSql` instead of manipulating `SqlValue`s directly.

EASY CONVERSIONS BETWEEN HASKELL TYPES

Conversions are powerful; for instance, you can call `fromSql` on a SqlInt32 and get a String or a Double out of it. This class attempts to Do The Right Thing whenever possible, and will raise an error when asked to do something incorrect. In particular, when converting to any type except a Maybe, `SqlNull` as the input will cause an error to be raised.

Conversions are implemented in terms of the Data.Convertible module, part of the convertible package. You can refer to its documentation, and import that module, if you wish to parse the Left result from `safeFromSql` yourself, or write your own conversion instances.

Here are some notes about conversion:

- Fractions of a second are not preserved on time values
- There is no `safeToSql` because `toSql` never fails.

See also `toSql`, `safeFromSql`, `fromSql`, `nToSql`, `iToSql`, `posixToSql`.

ERROR CONDITIONS

There may sometimes be an error during conversion. For instance, if you have a `SqlString` and are attempting to convert it to an Integer, but it doesn't parse as an Integer, you will get an error. This will be indicated as an exception if using `fromSql`, or a Left result if using `safeFromSql`.

SPECIAL NOTE ON POSIXTIME

Note that a `NominalDiffTime` or `POSIXTime` is converted to `SqlDiffTime` by `toSql`. HDBC cannot differentiate between `NominalDiffTime` and `POSIXTime` since they are the same underlying type. You must construct `SqlPOSIXTime` manually or via `posixToSql`, or use `SqlUTCTime`.

DETAILS ON SQL TYPES

HDBC database backends are expected to marshal date and time data back and forth using the appropriate representation for the underlying database engine. Databases such as PostgreSQL with builtin date and time types should see automatic conversion between these Haskell types to database types. Other databases will be presented with an integer or a string. Care should be taken to use the same type on the Haskell side as you use on the database side. For instance, if your database type lacks timezone information, you ought not to use ZonedTime, but instead LocalTime or UTCTime. Database type systems are not always as rich as Haskell. For instance, for data stored in a TIMESTAMP WITHOUT TIME ZONE column, HDBC may not be able to tell if it is intended as UTCTime or LocalTime data, and will happily convert it to both, upon your request. It is your responsibility to ensure that you treat timezone issues with due care.

This behavior also exists for other types. For instance, many databases do not have a Rational type, so they will just use the show function and store a Rational as a string.

The conversion between Haskell types and database types is complex, and generic code in HDBC or its backends cannot possibly accomodate every possible situation. In some cases, you may be best served by converting your Haskell type to a String, and passing that to the database.

UNICODE AND BYTESTRINGS

Beginning with HDBC v2.0, interactions with a database are presumed to occur in UTF-8.

To accomplish this, whenever a ByteString must be converted to or from a String, the ByteString is assumed to be in UTF-8 encoding, and will be decoded or encoded as appropriate. Database drivers will generally present text or string data they have received from the database as a SqlValue holding a ByteString, which `fromSql` will automatically convert to a String, and thus automatically decode UTF-8, when you need it. In the other direction, database drivers will generally convert a `SqlString` to a ByteString in UTF-8 encoding before passing it to the database engine.

If you are handling some sort of binary data that is not in UTF-8, you can of course work with the ByteString directly, which will bypass any conversion.

Due to lack of support by database engines, lazy ByteStrings are not passed to database drivers. When you use `toSql` on a lazy ByteString, it will be converted to a strict ByteString for storage. Similarly, `fromSql` will convert a strict ByteString to a lazy ByteString if you demand it.

EQUALITY OF SQLVALUE

Two SqlValues are considered to be equal if one of these hold. The first comparison that can be made is controlling; if none of these comparisons can be made, then they are not equal:

- Both are NULL
- Both represent the same type and the encapsulated values are considered equal by applying (==) to them
- The values of each, when converted to a string, are equal

STRING VERSIONS OF TIMES

Default string representations are given as comments below where such are non-obvious. These are used for `fromSql` when a `String` is desired. They are also defaults for representing data to SQL backends, though individual backends may override them when a different format is demanded by the underlying database. Date and time formats use ISO8601 date format, with HH:MM:SS added for time, and -HHMM added for timezone offsets.

DEPRECATED CONSTRUCTORS

`SqlEpochTime` and `SqlTimeDiff` are no longer created automatically by any `toSql` or `fromSql` functions or database backends. They may still be manually constructed, but are expected to be removed in a future version. Although these two constructures will be removed, support for marshalling to and from the old System.Time data will be maintained as long as System.Time is, simply using the newer data types for conversion.

Constructors

SqlString String |
SqlByteString ByteString |
SqlWord32 Word32 |
SqlWord64 Word64 |
SqlInt32 Int32 |
SqlInt64 Int64 |
SqlInteger Integer |
SqlChar Char |
SqlBool Bool |
SqlDouble Double |
SqlRational Rational |
SqlLocalDate Day | Local YYYY-MM-DD (no timezone).
SqlLocalTimeOfDay TimeOfDay | Local HH:MM:SS (no timezone).
SqlZonedLocalTimeOfDay TimeOfDay TimeZone | Local HH:MM:SS -HHMM. Converts to and from (TimeOfDay, TimeZone).
SqlLocalTime LocalTime | Local YYYY-MM-DD HH:MM:SS (no timezone).
SqlZonedTime ZonedTime | Local YYYY-MM-DD HH:MM:SS -HHMM. Considered equal if both convert to the same UTC time.
SqlUTCTime UTCTime | UTC YYYY-MM-DD HH:MM:SS.
SqlDiffTime NominalDiffTime | Calendar diff between seconds. Rendered as Integer when converted to String, but greater precision may be preserved for other types or to underlying database.
SqlPOSIXTime POSIXTime | Time as seconds since midnight Jan 1 1970 UTC. Integer rendering as for `SqlDiffTime`.
SqlEpochTime Integer | DEPRECATED Representation of ClockTime or CalendarTime. Use SqlPOSIXTime instead.
SqlTimeDiff Integer | DEPRECATED Representation of TimeDiff. Use SqlDiffTime instead.
SqlNull | NULL in SQL or Nothing in Haskell.

Instances

Eq SqlValue # |
Methods (==) :: SqlValue -> SqlValue -> Bool # (/=) :: SqlValue -> SqlValue -> Bool #
Show SqlValue # |
Methods showsPrec :: Int -> SqlValue -> ShowS # show :: SqlValue -> String # showList :: [SqlValue] -> ShowS #
Convertible Bool SqlValue # |
Methods safeConvert :: Bool -> ConvertResult SqlValue #
Convertible Char SqlValue # |
Methods safeConvert :: Char -> ConvertResult SqlValue #
Convertible Double SqlValue # |
Methods safeConvert :: Double -> ConvertResult SqlValue #
Convertible Int SqlValue # |
Methods safeConvert :: Int -> ConvertResult SqlValue #
Convertible Int32 SqlValue # |
Methods safeConvert :: Int32 -> ConvertResult SqlValue #
Convertible Int64 SqlValue # |
Methods safeConvert :: Int64 -> ConvertResult SqlValue #
Convertible Integer SqlValue # |
Methods safeConvert :: Integer -> ConvertResult SqlValue #
Convertible Rational SqlValue # |
Methods safeConvert :: Rational -> ConvertResult SqlValue #
Convertible Word32 SqlValue # |
Methods safeConvert :: Word32 -> ConvertResult SqlValue #
Convertible Word64 SqlValue # |
Methods safeConvert :: Word64 -> ConvertResult SqlValue #
Convertible String SqlValue # |
Methods safeConvert :: String -> ConvertResult SqlValue #
Convertible ByteString SqlValue # |
Methods safeConvert :: ByteString -> ConvertResult SqlValue #
Convertible ByteString SqlValue # |
Methods safeConvert :: ByteString -> ConvertResult SqlValue #
Convertible ClockTime SqlValue # |
Methods safeConvert :: ClockTime -> ConvertResult SqlValue #
Convertible CalendarTime SqlValue # |
Methods safeConvert :: CalendarTime -> ConvertResult SqlValue #
Convertible TimeDiff SqlValue # |
Methods safeConvert :: TimeDiff -> ConvertResult SqlValue #
Convertible Text SqlValue # |
Methods safeConvert :: Text -> ConvertResult SqlValue #
Convertible Text SqlValue # |
Methods safeConvert :: Text -> ConvertResult SqlValue #
Convertible ZonedTime SqlValue # |
Methods safeConvert :: ZonedTime -> ConvertResult SqlValue #
Convertible LocalTime SqlValue # |
Methods safeConvert :: LocalTime -> ConvertResult SqlValue #
Convertible TimeOfDay SqlValue # |
Methods safeConvert :: TimeOfDay -> ConvertResult SqlValue #
Convertible UTCTime SqlValue # |
Methods safeConvert :: UTCTime -> ConvertResult SqlValue #
Convertible NominalDiffTime SqlValue # |
Methods safeConvert :: NominalDiffTime -> ConvertResult SqlValue #
Convertible DiffTime SqlValue # |
Methods safeConvert :: DiffTime -> ConvertResult SqlValue #
Convertible Day SqlValue # |
Methods safeConvert :: Day -> ConvertResult SqlValue #
Convertible SqlValue Bool # |
Methods safeConvert :: SqlValue -> ConvertResult Bool #
Convertible SqlValue Char # |
Methods safeConvert :: SqlValue -> ConvertResult Char #
Convertible SqlValue Double # |
Methods safeConvert :: SqlValue -> ConvertResult Double #
Convertible SqlValue Int # |
Methods safeConvert :: SqlValue -> ConvertResult Int #
Convertible SqlValue Int32 # |
Methods safeConvert :: SqlValue -> ConvertResult Int32 #
Convertible SqlValue Int64 # |
Methods safeConvert :: SqlValue -> ConvertResult Int64 #
Convertible SqlValue Integer # |
Methods safeConvert :: SqlValue -> ConvertResult Integer #
Convertible SqlValue Rational # |
Methods safeConvert :: SqlValue -> ConvertResult Rational #
Convertible SqlValue Word32 # |
Methods safeConvert :: SqlValue -> ConvertResult Word32 #
Convertible SqlValue Word64 # |
Methods safeConvert :: SqlValue -> ConvertResult Word64 #
Convertible SqlValue String # |
Methods safeConvert :: SqlValue -> ConvertResult String #
Convertible SqlValue ByteString # |
Methods safeConvert :: SqlValue -> ConvertResult ByteString #
Convertible SqlValue ByteString # |
Methods safeConvert :: SqlValue -> ConvertResult ByteString #
Convertible SqlValue ClockTime # |
Methods safeConvert :: SqlValue -> ConvertResult ClockTime #
Convertible SqlValue CalendarTime # |
Methods safeConvert :: SqlValue -> ConvertResult CalendarTime #
Convertible SqlValue TimeDiff # |
Methods safeConvert :: SqlValue -> ConvertResult TimeDiff #
Convertible SqlValue Text # |
Methods safeConvert :: SqlValue -> ConvertResult Text #
Convertible SqlValue Text # |
Methods safeConvert :: SqlValue -> ConvertResult Text #
Convertible SqlValue ZonedTime # |
Methods safeConvert :: SqlValue -> ConvertResult ZonedTime #
Convertible SqlValue LocalTime # |
Methods safeConvert :: SqlValue -> ConvertResult LocalTime #
Convertible SqlValue TimeOfDay # |
Methods safeConvert :: SqlValue -> ConvertResult TimeOfDay #
Convertible SqlValue UTCTime # |
Methods safeConvert :: SqlValue -> ConvertResult UTCTime #
Convertible SqlValue NominalDiffTime # |
Methods safeConvert :: SqlValue -> ConvertResult NominalDiffTime #
Convertible SqlValue DiffTime # |
Methods safeConvert :: SqlValue -> ConvertResult DiffTime #
Convertible SqlValue Day # |
Methods safeConvert :: SqlValue -> ConvertResult Day #
Convertible SqlValue SqlValue # |
Methods safeConvert :: SqlValue -> ConvertResult SqlValue #
Convertible SqlValue a => Convertible SqlValue (Maybe a) # |
Methods safeConvert :: SqlValue -> ConvertResult (Maybe a) #
Convertible SqlValue (TimeOfDay, TimeZone) # |
Methods safeConvert :: SqlValue -> ConvertResult (TimeOfDay, TimeZone) #
Convertible a SqlValue => Convertible (Maybe a) SqlValue # |
Methods safeConvert :: Maybe a -> ConvertResult SqlValue #
Convertible (TimeOfDay, TimeZone) SqlValue # |
Methods safeConvert :: (TimeOfDay, TimeZone) -> ConvertResult SqlValue #

data ConnWrapper #

Sometimes, it is annoying to use typeclasses with Haskell's type system. In those situations, you can use a ConnWrapper. You can create one with:

    let wrapped = ConnWrapper iconn

You can then use this directly, since a ConnWrapper is also an `IConnection`. However, you will not be able to use private database functions on it.

Or, you can use `withWConn`.

Constructors

IConnection conn => ConnWrapper conn |

Instances

IConnection ConnWrapper # |
Methods disconnect :: ConnWrapper -> IO () # commit :: ConnWrapper -> IO () # rollback :: ConnWrapper -> IO () # runRaw :: ConnWrapper -> String -> IO () # run :: ConnWrapper -> String -> [SqlValue] -> IO Integer # prepare :: ConnWrapper -> String -> IO Statement # clone :: ConnWrapper -> IO ConnWrapper # hdbcDriverName :: ConnWrapper -> String # hdbcClientVer :: ConnWrapper -> String # proxiedClientName :: ConnWrapper -> String # proxiedClientVer :: ConnWrapper -> String # dbServerVer :: ConnWrapper -> String # dbTransactionSupport :: ConnWrapper -> Bool # getTables :: ConnWrapper -> IO [String] # describeTable :: ConnWrapper -> String -> IO [(String, SqlColDesc)] #

withWConn :: forall b. ConnWrapper -> (forall conn. IConnection conn => conn -> b) -> b #

Unwrap a `ConnWrapper` and pass the embedded `IConnection` to a function. Example:

    withWConn wrapped run $ "SELECT * from foo where bar = 1" []