direct-sqlite-2.3.14: Low-level binding to SQLite3. Includes UTF8 and BLOB support.

Safe HaskellNone
LanguageHaskell2010

Database.SQLite3.Direct

Contents

Description

This API is a slightly lower-level version of Database.SQLite3. Namely:

  • It returns errors instead of throwing them.
  • It only uses cheap conversions. None of these bindings convert from String or Text.

Synopsis

Connection management

setTrace :: Database -> Maybe (Utf8 -> IO ()) -> IO () Source

http://www.sqlite.org/c3ref/profile.html

Enable/disable tracing of SQL execution. Tracing can be disabled by setting Nothing as the logger callback.

Warning: If the logger callback throws an exception, your whole program will crash. Enable only for debugging!

getAutoCommit :: Database -> IO Bool Source

http://www.sqlite.org/c3ref/get_autocommit.html

Return True if the connection is in autocommit mode, or False if a transaction started with BEGIN is still active.

Be warned that some errors roll back the transaction automatically, and that ROLLBACK will throw an error if no transaction is active. Use getAutoCommit to avoid such an error:

 autocommit <- getAutoCommit conn
 when (not autocommit) $
     exec conn "ROLLBACK"

Simple query execution

execWithCallback :: Database -> Utf8 -> ExecCallback -> IO (Either (Error, Utf8) ()) Source

Like exec, but invoke the callback for each result row.

If the callback throws an exception, it will be rethrown by execWithCallback.

type ExecCallback Source

Arguments

 = ColumnCount

Number of columns, which is the number of items in the following lists. This will be the same for every row.

-> [Utf8]

List of column names. This will be the same for every row.

-> [Maybe Utf8]

List of column values, as returned by columnText.

-> IO () 

Statement management

prepare :: Database -> Utf8 -> IO (Either Error (Maybe Statement)) Source

http://www.sqlite.org/c3ref/prepare.html

If the query contains no SQL statements, this returns Right Nothing.

reset :: Statement -> IO (Either Error ()) Source

http://www.sqlite.org/c3ref/reset.html

Warning:

  • If the most recent step call failed, this will return the corresponding error.
  • This does not reset the bindings on a prepared statement. Use clearBindings to do that.

finalize :: Statement -> IO (Either Error ()) Source

http://www.sqlite.org/c3ref/finalize.html

Warning: If the most recent step call failed, this will return the corresponding error.

clearBindings :: Statement -> IO () Source

http://www.sqlite.org/c3ref/clear_bindings.html

Set all parameters in the prepared statement to null.

statementSql :: Statement -> IO (Maybe Utf8) Source

http://www.sqlite.org/c3ref/sql.html

Return a copy of the original SQL text used to compile the statement.

Parameter and column information

bindParameterCount :: Statement -> IO ParamIndex Source

http://www.sqlite.org/c3ref/bind_parameter_count.html

This returns the index of the largest (rightmost) parameter. Note that this is not necessarily the number of parameters. If numbered parameters like ?5 are used, there may be gaps in the list.

See ParamIndex for more information.

Binding values to a prepared statement

Reading the result row

control loading of extensions

Result statistics

changes :: Database -> IO Int Source

http://www.sqlite.org/c3ref/changes.html

Return the number of rows that were changed, inserted, or deleted by the most recent INSERT, DELETE, or UPDATE statement.

totalChanges :: Database -> IO Int Source

http://www.sqlite.org/c3ref/total_changes.html

Return the total number of row changes caused by INSERT, DELETE, or UPDATE statements since the Database was opened.

Create custom SQL functions

createFunction Source

Arguments

:: Database 
-> Utf8

Name of the function.

-> Maybe ArgCount

Number of arguments. Nothing means that the function accepts any number of arguments.

-> Bool

Is the function deterministic?

-> (FuncContext -> FuncArgs -> IO ())

Implementation of the function.

-> IO (Either Error ()) 

http://sqlite.org/c3ref/create_function.html

Create a custom SQL function or redefine the behavior of an existing function.

createAggregate Source

Arguments

:: Database 
-> Utf8

Name of the function.

-> Maybe ArgCount

Number of arguments.

-> a

Initial aggregate state.

-> (FuncContext -> FuncArgs -> a -> IO a)

Process one row and update the aggregate state.

-> (FuncContext -> a -> IO ())

Called after all rows have been processed. Can be used to construct the returned value from the aggregate state.

-> IO (Either Error ()) 

Like createFunction except that it creates an aggregate function.

deleteFunction :: Database -> Utf8 -> Maybe ArgCount -> IO (Either Error ()) Source

Delete an SQL function (scalar or aggregate).

Extract function arguments

Set the result of a function

Create custom collations

createCollation Source

Arguments

:: Database 
-> Utf8

Name of the collation.

-> (Utf8 -> Utf8 -> Ordering)

Comparison function.

-> IO (Either Error ()) 

deleteCollation :: Database -> Utf8 -> IO (Either Error ()) Source

Delete a collation.

Interrupting a long-running query

interrupt :: Database -> IO () Source

http://www.sqlite.org/c3ref/interrupt.html

Cause any pending operation on the Database handle to stop at its earliest opportunity. This simply sets a flag and returns immediately. It does not wait for the pending operation to finish.

You'll need to compile with -threaded for this to do any good. Without -threaded, FFI calls block the whole RTS, meaning interrupt would never run at the same time as step.

Types

newtype Database Source

Constructors

Database (Ptr CDatabase) 

Instances

newtype Statement Source

Constructors

Statement (Ptr CStatement) 

newtype FuncContext Source

The context in which a custom SQL function is executed.

Constructors

FuncContext (Ptr CContext) 

data FuncArgs Source

The arguments of a custom SQL function.

Constructors

FuncArgs CArgCount (Ptr (Ptr CValue)) 

Results and errors

data StepResult Source

Constructors

Row 
Done 

data Error Source

Constructors

ErrorOK

Successful result

ErrorError

SQL error or missing database

ErrorInternal

Internal logic error in SQLite

ErrorPermission

Access permission denied

ErrorAbort

Callback routine requested an abort

ErrorBusy

The database file is locked

ErrorLocked

A table in the database is locked

ErrorNoMemory

A malloc() failed

ErrorReadOnly

Attempt to write a readonly database

ErrorInterrupt

Operation terminated by sqlite3_interrupt()

ErrorIO

Some kind of disk I/O error occurred

ErrorCorrupt

The database disk image is malformed

ErrorNotFound

Unknown opcode in sqlite3_file_control()

ErrorFull

Insertion failed because database is full

ErrorCan'tOpen

Unable to open the database file

ErrorProtocol

Database lock protocol error

ErrorEmpty

Database is empty

ErrorSchema

The database schema changed

ErrorTooBig

String or BLOB exceeds size limit

ErrorConstraint

Abort due to constraint violation

ErrorMismatch

Data type mismatch

ErrorMisuse

Library used incorrectly

ErrorNoLargeFileSupport

Uses OS features not supported on host

ErrorAuthorization

Authorization denied

ErrorFormat

Auxiliary database format error

ErrorRange

2nd parameter to sqlite3_bind out of range

ErrorNotADatabase

File opened that is not a database file

ErrorRow

sqlite3_step() has another row ready

ErrorDone

sqlite3_step() has finished executing

Special types

newtype Utf8 Source

A ByteString containing UTF8-encoded text with no NUL characters.

Constructors

Utf8 ByteString 

Instances

Eq Utf8 
Ord Utf8 
Show Utf8 
IsString Utf8
fromString = Utf8 . encodeUtf8 . pack
Monoid Utf8 

newtype ParamIndex Source

Index of a parameter in a parameterized query. Parameter indices start from 1.

When a query is prepared, SQLite allocates an array indexed from 1 to the highest parameter index. For example:

>Right stmt <- prepare conn "SELECT ?1, ?5, ?3, ?"
>bindParameterCount stmt
ParamIndex 6

This will allocate an array indexed from 1 to 6 (? takes the highest preceding index plus one). The array is initialized with null values. When you bind a parameter with bindSQLData, it assigns a new value to one of these indices.

See http://www.sqlite.org/lang_expr.html#varparam for the syntax of parameter placeholders, and how parameter indices are assigned.

Constructors

ParamIndex Int 

Instances

Bounded ParamIndex

Limit min/max bounds to fit into SQLite's native parameter ranges.

Enum ParamIndex 
Eq ParamIndex 
Integral ParamIndex 
Num ParamIndex 
Ord ParamIndex 
Real ParamIndex 
Show ParamIndex

This just shows the underlying integer, without the data constructor.

FFIType ParamIndex CParamIndex 

newtype ColumnIndex Source

Index of a column in a result set. Column indices start from 0.

Constructors

ColumnIndex Int 

Instances

Bounded ColumnIndex

Limit min/max bounds to fit into SQLite's native parameter ranges.

Enum ColumnIndex 
Eq ColumnIndex 
Integral ColumnIndex 
Num ColumnIndex 
Ord ColumnIndex 
Real ColumnIndex 
Show ColumnIndex

This just shows the underlying integer, without the data constructor.

FFIType ColumnIndex CColumnIndex 

type ColumnCount = ColumnIndex Source

Number of columns in a result set.

newtype ArgCount Source

Number of arguments of a user defined SQL function.

Constructors

ArgCount Int 

Instances

Bounded ArgCount 
Enum ArgCount 
Eq ArgCount 
Integral ArgCount 
Num ArgCount 
Ord ArgCount 
Real ArgCount 
Show ArgCount

This just shows the underlying integer, without the data constructor.

FFIType ArgCount CArgCount 

type ArgIndex = ArgCount Source

Index of an argument to a custom function. Indices start from 0.