direct-sqlite-2.3.13: Low-level binding to SQLite3. Includes UTF8 and BLOB support.

Safe HaskellNone

Database.SQLite3

Contents

Synopsis

Connection management

Simple query execution

exec :: Database -> Text -> IO ()Source

Execute zero or more SQL statements delimited by semicolons.

execPrint :: Database -> Text -> IO ()Source

Like exec, but print result rows to stdout.

This is mainly for convenience when experimenting in GHCi. The output format may change in the future.

execWithCallback :: Database -> Text -> ExecCallback -> IO ()Source

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

type ExecCallbackSource

Arguments

 = ColumnCount

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

-> [Text]

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

-> [Maybe Text]

List of column values, as returned by columnText.

-> IO () 

Statement management

prepare :: Database -> Text -> IO StatementSource

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

Unlike exec, prepare only executes the first statement, and ignores subsequent statements.

If the query string contains no SQL statements, this fails.

prepareUtf8 :: Database -> Utf8 -> IO StatementSource

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

It can help to avoid redundant Utf8 to Text conversion if you already have Utf8

If the query string contains no SQL statements, this fails.

reset :: Statement -> IO ()Source

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

Note that in the C API, sqlite3_reset returns an error code if the most recent sqlite3_step indicated an error. We do not replicate that behavior here. reset never throws an exception.

clearBindings :: Statement -> IO ()Source

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

Set all parameters in the prepared statement to null.

Parameter and column information

bindParameterCount :: Statement -> IO ParamIndexSource

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.

bindParameterName :: Statement -> ParamIndex -> IO (Maybe Text)Source

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

Return the N-th SQL parameter name.

Named parameters are returned as-is. E.g. ":v" is returned as Just ":v". Unnamed parameters, however, are converted to Nothing.

Note that the parameter index starts at 1, not 0.

columnName :: Statement -> ColumnIndex -> IO (Maybe Text)Source

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

Return the name of a result column. If the column index is out of range, return Nothing.

Binding values to a prepared statement

bindSQLData :: Statement -> ParamIndex -> SQLData -> IO ()Source

If the index is not between 1 and bindParameterCount inclusive, this fails with ErrorRange. Otherwise, it succeeds, even if the query skips this index by using numbered parameters.

Example:

> stmt <- prepare conn "SELECT ?1, ?3, ?5"
> bindSQLData stmt 1 (SQLInteger 1)
> bindSQLData stmt 2 (SQLInteger 2)
> bindSQLData stmt 6 (SQLInteger 6)
*** Exception: SQLite3 returned ErrorRange while attempting to perform bind int64.
> step stmt >> columns stmt
[SQLInteger 1,SQLNull,SQLNull]

bind :: Statement -> [SQLData] -> IO ()Source

Convenience function for binding values to all parameters. This will fail if the list has the wrong number of parameters.

Reading the result row

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

Warning: column and columns will throw a DecodeError if any TEXT datum contains invalid UTF-8.

typedColumns :: Statement -> [Maybe ColumnType] -> IO [SQLData]Source

This avoids extra API calls using the list of column types. If passed types do not correspond to the actual types, the values will be converted according to the rules at http://www.sqlite.org/c3ref/column_blob.html. If the list contains more items that number of columns, the result is undefined.

columnText :: Statement -> ColumnIndex -> IO TextSource

This will throw a DecodeError if the datum contains invalid UTF-8. If this behavior is undesirable, you can use columnText from Database.SQLite3.Direct, which does not perform conversion to Text.

Result statistics

changes :: Database -> IO IntSource

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.

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.

interruptibly :: Database -> IO a -> IO aSource

Make it possible to interrupt the given database operation with an asynchronous exception. This only works if the program is compiled with base >= 4.3 and -threaded.

It works by running the callback in a forked thread. If interrupted, it uses interrupt to try to stop the operation.

Types

data SQLError Source

Exception thrown when SQLite3 reports an error.

direct-sqlite may throw other types of exceptions if you misuse the API.

Constructors

SQLError 

Fields

sqlError :: !Error

Error code returned by API call

sqlErrorDetails :: Text

Text describing the error

sqlErrorContext :: Text

Indicates what action produced this error, e.g. exec "SELECT * FROM foo"

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 integers

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 = ColumnIndexSource

Number of columns in a result set.