hsql-1.7 Contents Index

Database.HSQL

Contents Connect/Disconnect Command Execution Functions Retrieving Statement values and types Transactions SQL Exceptions handling Utilities Metadata Extra types

Description

Synopsis

data Connection disconnect :: Connection -> IO () execute :: Connection -> String -> IO () data Statement query :: Connection -> String -> IO Statement closeStatement :: Statement -> IO () fetch :: Statement -> IO Bool type FieldDef = (String, SqlType, Bool) data SqlType = SqlChar Int | SqlVarChar Int | SqlLongVarChar Int | SqlText | SqlWChar Int | SqlWVarChar Int | SqlWLongVarChar Int | SqlDecimal Int Int | SqlNumeric Int Int | SqlSmallInt | SqlMedInt | SqlInteger | SqlReal | SqlFloat | SqlDouble | SqlBit | SqlTinyInt | SqlBigInt | SqlBinary Int | SqlVarBinary Int | SqlLongVarBinary Int | SqlDate | SqlTime | SqlTimeTZ | SqlAbsTime | SqlRelTime | SqlTimeInterval | SqlAbsTimeInterval | SqlTimeStamp | SqlDateTime | SqlDateTimeTZ | SqlYear | SqlSET | SqlENUM | SqlBLOB | SqlMoney | SqlINetAddr | SqlCIDRAddr | SqlMacAddr | SqlPoint | SqlLSeg | SqlPath | SqlBox | SqlPolygon | SqlLine | SqlCircle | SqlUnknown Int class SqlBind a where toSqlValue :: a -> String toSqlValue :: SqlBind a => a -> String getFieldValue :: SqlBind a => Statement -> String -> IO a getFieldValueMB :: SqlBind a => Statement -> String -> IO (Maybe a) getFieldValue' :: SqlBind a => Statement -> String -> a -> IO a getFieldValueType :: Statement -> String -> (SqlType, Bool) getFieldsTypes :: Statement -> [(String, SqlType, Bool)] inTransaction :: Connection -> (Connection -> IO a) -> IO a data SqlError = SqlError { seState :: String seNativeError :: Int seErrorMsg :: String } | SqlNoData | SqlInvalidHandle | SqlStillExecuting | SqlNeedData | SqlBadTypeCast { seFieldName :: String seFieldType :: SqlType } | SqlFetchNull { seFieldName :: String } | SqlUnknownField { seFieldName :: String } | SqlUnsupportedOperation | SqlClosedHandle catchSql :: IO a -> (SqlError -> IO a) -> IO a handleSql :: (SqlError -> IO a) -> IO a -> IO a sqlExceptions :: Exception -> Maybe SqlError forEachRow :: (Statement -> s -> IO s) -> Statement -> s -> IO s forEachRow' :: (Statement -> IO ()) -> Statement -> IO () collectRows :: (Statement -> IO a) -> Statement -> IO [a] tables :: Connection -> IO [String] describe :: Connection -> String -> IO [FieldDef] data Point = Point Double Double data Line = Line Point Point data Path = OpenPath [Point] | ClosedPath [Point] data Box = Box Double Double Double Double data Circle = Circle Point Double data Polygon = Polygon [Point]

Connect/Disconnect

data Connection

A Connection type represents a connection to a database, through which you can operate on the it. In order to create the connection you need to use the connect function from the module for your prefered backend.

disconnect :: Connection -> IO ()

Closes the connection. Performing disconnect on a connection that has already been closed has no effect. All other operations on a closed connection will fail.

Command Execution Functions

Once a connection to a database has been successfully established, the functions described here are used to perform SQL queries and commands.

execute

:: Connection the database connection -> String the text of SQL command -> IO () Submits a command to the database.

data Statement

The Statement type represents a result from the execution of given SQL query.

query

:: Connection the database connection -> String the text of SQL query -> IO Statement the associated statement. Must be closed with the closeStatement function Executes a query and returns a result set

closeStatement :: Statement -> IO ()

closeStatement stops processing associated with a specific statement, closes any open cursors associated with the statement, discards pending results, and frees all resources associated with the statement. Performing closeStatement on a statement that has already been closed has no effect. All other operations on a closed statement will fail.

fetch :: Statement -> IO Bool

fetch fetches the next rowset of data from the result set. The values from columns can be retrieved with getFieldValue function.

Retrieving Statement values and types

type FieldDef = (String, SqlType, Bool)

data SqlType

Constructors SqlChar Int SqlVarChar Int SqlLongVarChar Int SqlText SqlWChar Int SqlWVarChar Int SqlWLongVarChar Int SqlDecimal Int Int SqlNumeric Int Int SqlSmallInt SqlMedInt SqlInteger SqlReal SqlFloat SqlDouble SqlBit SqlTinyInt SqlBigInt SqlBinary Int SqlVarBinary Int SqlLongVarBinary Int SqlDate SqlTime SqlTimeTZ SqlAbsTime SqlRelTime SqlTimeInterval SqlAbsTimeInterval SqlTimeStamp SqlDateTime SqlDateTimeTZ SqlYear SqlSET SqlENUM SqlBLOB SqlMoney SqlINetAddr SqlCIDRAddr SqlMacAddr SqlPoint SqlLSeg SqlPath SqlBox SqlPolygon SqlLine SqlCircle SqlUnknown Int HSQL returns SqlUnknown tp for all columns for which it cannot determine the right type. The tp here is the internal type code returned from the backend library Instances Eq SqlType Show SqlType

class SqlBind a where

Methods toSqlValue :: a -> String Instances SqlBind Bool SqlBind Box SqlBind Circle SqlBind ClockTime SqlBind Double SqlBind Float SqlBind INetAddr SqlBind Int SqlBind Int64 SqlBind Integer SqlBind Line SqlBind MacAddr SqlBind Path SqlBind Point SqlBind Polygon SqlBind String SqlBind a => SqlBind (Maybe a)

toSqlValue :: SqlBind a => a -> String

getFieldValue

:: SqlBind a => Statement -> String Field name -> IO a Field value Retrieves the value of field with the specified name.

getFieldValueMB :: SqlBind a => Statement -> String -> IO (Maybe a)

getFieldValue'

:: SqlBind a => Statement -> String Field name -> a Default field value -> IO a Field value Retrieves the value of field with the specified name. If the field value is null then the function will return the default value.

getFieldValueType :: Statement -> String -> (SqlType, Bool)

Returns the type and the nullable flag for field with specified name

getFieldsTypes :: Statement -> [(String, SqlType, Bool)]

Returns the list of fields with their types and nullable flags

Transactions

inTransaction

:: Connection -> (Connection -> IO a) an action -> IO a the returned value is the result returned from action The inTransaction function executes the specified action in transaction mode. If the action completes successfully then the transaction will be commited. If the action completes with an exception then the transaction will be rolled back and the exception will be throw again.

SQL Exceptions handling

data SqlError

Constructors SqlError seState :: String seNativeError :: Int seErrorMsg :: String SqlNoData SqlInvalidHandle SqlStillExecuting SqlNeedData SqlBadTypeCast seFieldName :: String seFieldType :: SqlType SqlFetchNull seFieldName :: String SqlUnknownField seFieldName :: String SqlUnsupportedOperation SqlClosedHandle Instances Show SqlError Typeable SqlError

catchSql :: IO a -> (SqlError -> IO a) -> IO a

handleSql :: (SqlError -> IO a) -> IO a -> IO a

sqlExceptions :: Exception -> Maybe SqlError

Utilities

forEachRow

:: (Statement -> s -> IO s) an action -> Statement the statement -> s initial state -> IO s final state The forEachRow function iterates through the result set in Statement and executes the given action for each row in the set. The function closes the Statement after the last row processing or if the given action raises an exception.

forEachRow' :: (Statement -> IO ()) -> Statement -> IO ()

The forEachRow function is analogous to forEachRow but doesn't provide state. The function closes the Statement after the last row processing or if the given action raises an exception.

collectRows :: (Statement -> IO a) -> Statement -> IO [a]

The collectRows function iterates through the result set in Statement and executes the given action for each row in the set. The values returned from action are collected and returned as list. The function closes the Statement after the last row processing or if the given action raises an exception.

Metadata

tables

:: Connection Database connection -> IO [String] The names of all tables in the database. List all tables in the database.

describe

:: Connection Database connection -> String Name of a database table -> IO [FieldDef] The list of fields in the table List all columns in a table along with their types and nullable flags

Extra types

data Point

Constructors Point Double Double Instances Eq Point Show Point SqlBind Point

data Line

Constructors Line Point Point Instances Eq Line Show Line SqlBind Line

data Path

Constructors OpenPath [Point] ClosedPath [Point] Instances Eq Path Show Path SqlBind Path

data Box

Constructors Box Double Double Double Double Instances Eq Box Show Box SqlBind Box

data Circle

Constructors Circle Point Double Instances Eq Circle Show Circle SqlBind Circle

data Polygon

Constructors Polygon [Point] Instances Eq Polygon Show Polygon SqlBind Polygon

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