Struct rusqlite::Connection
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pub struct Connection { /* fields omitted */ }
A connection to a SQLite database.
Methods
impl Connection
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fn transaction(&mut self) -> Result<Transaction>
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Begin a new transaction with the default behavior (DEFERRED).
The transaction defaults to rolling back when it is dropped. If you want the transaction to
commit, you must call commit
or set_drop_behavior(DropBehavior::Commit)
.
Example
fn perform_queries(conn: &mut Connection) -> Result<()> { let tx = try!(conn.transaction()); try!(do_queries_part_1(&tx)); // tx causes rollback if this fails try!(do_queries_part_2(&tx)); // tx causes rollback if this fails tx.commit() }
Failure
Will return Err
if the underlying SQLite call fails.
fn transaction_with_behavior(
&mut self,
behavior: TransactionBehavior
) -> Result<Transaction>
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&mut self,
behavior: TransactionBehavior
) -> Result<Transaction>
Begin a new transaction with a specified behavior.
See transaction
.
Failure
Will return Err
if the underlying SQLite call fails.
fn savepoint(&mut self) -> Result<Savepoint>
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Begin a new savepoint with the default behavior (DEFERRED).
The savepoint defaults to rolling back when it is dropped. If you want the savepoint to
commit, you must call commit
or set_drop_behavior(DropBehavior::Commit)
.
Example
fn perform_queries(conn: &mut Connection) -> Result<()> { let sp = try!(conn.savepoint()); try!(do_queries_part_1(&sp)); // sp causes rollback if this fails try!(do_queries_part_2(&sp)); // sp causes rollback if this fails sp.commit() }
Failure
Will return Err
if the underlying SQLite call fails.
fn savepoint_with_name<T: Into<String>>(&mut self, name: T) -> Result<Savepoint>
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Begin a new savepoint with a specified name.
See savepoint
.
Failure
Will return Err
if the underlying SQLite call fails.
impl Connection
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fn prepare_cached<'a>(&'a self, sql: &str) -> Result<CachedStatement<'a>>
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Prepare a SQL statement for execution, returning a previously prepared (but
not currently in-use) statement if one is available. The returned statement
will be cached for reuse by future calls to prepare_cached
once it is
dropped.
fn insert_new_people(conn: &Connection) -> Result<()> { { let mut stmt = try!(conn.prepare_cached("INSERT INTO People (name) VALUES (?)")); try!(stmt.execute(&[&"Joe Smith"])); } { // This will return the same underlying SQLite statement handle without // having to prepare it again. let mut stmt = try!(conn.prepare_cached("INSERT INTO People (name) VALUES (?)")); try!(stmt.execute(&[&"Bob Jones"])); } Ok(()) }
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn set_prepared_statement_cache_capacity(&self, capacity: usize)
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Set the maximum number of cached prepared statements this connection will hold. By default, a connection will hold a relatively small number of cached statements. If you need more, or know that you will not use cached statements, you can set the capacity manually using this method.
fn flush_prepared_statement_cache(&self)
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impl Connection
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fn trace(&mut self, trace_fn: Option<fn(_: &str)>)
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Register or clear a callback function that can be used for tracing the execution of SQL statements.
Prepared statement placeholders are replaced/logged with their assigned values. There can only be a single tracer defined for each database connection. Setting a new tracer clears the old one.
fn profile(&mut self, profile_fn: Option<fn(_: &str, _: Duration)>)
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Register or clear a callback function that can be used for profiling the execution of SQL statements.
There can only be a single profiler defined for each database connection. Setting a new profiler clears the old one.
impl Connection
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fn backup<P: AsRef<Path>>(
&self,
name: DatabaseName,
dst_path: P,
progress: Option<fn(_: Progress)>
) -> Result<()>
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&self,
name: DatabaseName,
dst_path: P,
progress: Option<fn(_: Progress)>
) -> Result<()>
Back up the name
database to the given destination path.
If progress
is not None
, it will be called periodically
until the backup completes.
For more fine-grained control over the backup process (e.g.,
to sleep periodically during the backup or to back up to an
already-open database connection), see the backup
module.
Failure
Will return Err
if the destination path cannot be opened
or if the backup fails.
fn restore<P: AsRef<Path>>(
&mut self,
name: DatabaseName,
src_path: P,
progress: Option<fn(_: Progress)>
) -> Result<()>
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&mut self,
name: DatabaseName,
src_path: P,
progress: Option<fn(_: Progress)>
) -> Result<()>
Restore the given source path into the name
database.
If progress
is not None
, it will be called periodically
until the restore completes.
For more fine-grained control over the restore process (e.g.,
to sleep periodically during the restore or to restore from an
already-open database connection), see the backup
module.
Failure
Will return Err
if the destination path cannot be opened
or if the restore fails.
impl Connection
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fn create_scalar_function<F, T>(
&self,
fn_name: &str,
n_arg: c_int,
deterministic: bool,
x_func: F
) -> Result<()> where
F: FnMut(&Context) -> Result<T>,
T: ToSql,
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&self,
fn_name: &str,
n_arg: c_int,
deterministic: bool,
x_func: F
) -> Result<()> where
F: FnMut(&Context) -> Result<T>,
T: ToSql,
Attach a user-defined scalar function to this database connection.
fn_name
is the name the function will be accessible from SQL.
n_arg
is the number of arguments to the function. Use -1
for a variable
number. If the function always returns the same value given the same
input, deterministic
should be true
.
The function will remain available until the connection is closed or
until it is explicitly removed via remove_function
.
Example
fn scalar_function_example(db: Connection) -> Result<()> { try!(db.create_scalar_function("halve", 1, true, |ctx| { let value = try!(ctx.get::<f64>(0)); Ok(value / 2f64) })); let six_halved: f64 = try!(db.query_row("SELECT halve(6)", &[], |r| r.get(0))); assert_eq!(six_halved, 3f64); Ok(()) }
Failure
Will return Err if the function could not be attached to the connection.
fn create_aggregate_function<A, D, T>(
&self,
fn_name: &str,
n_arg: c_int,
deterministic: bool,
aggr: D
) -> Result<()> where
D: Aggregate<A, T>,
T: ToSql,
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&self,
fn_name: &str,
n_arg: c_int,
deterministic: bool,
aggr: D
) -> Result<()> where
D: Aggregate<A, T>,
T: ToSql,
Attach a user-defined aggregate function to this database connection.
Failure
Will return Err if the function could not be attached to the connection.
fn remove_function(&self, fn_name: &str, n_arg: c_int) -> Result<()>
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Removes a user-defined function from this database connection.
fn_name
and n_arg
should match the name and number of arguments
given to create_scalar_function
or create_aggregate_function
.
Failure
Will return Err if the function could not be removed.
impl Connection
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fn blob_open<'a>(
&'a self,
db: DatabaseName,
table: &str,
column: &str,
row: i64,
read_only: bool
) -> Result<Blob<'a>>
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&'a self,
db: DatabaseName,
table: &str,
column: &str,
row: i64,
read_only: bool
) -> Result<Blob<'a>>
Open a handle to the BLOB located in row
, column
, table
in database db
.
Failure
Will return Err
if db
/table
/column
cannot be converted to a C-compatible string
or if the underlying SQLite BLOB open call fails.
impl Connection
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fn limit(&self, limit: Limit) -> i32
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Returns the current value of a limit.
fn set_limit(&self, limit: Limit, new_val: i32) -> i32
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Changes the limit to new_val
, returning the prior value of the limit.
impl Connection
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fn open<P: AsRef<Path>>(path: P) -> Result<Connection>
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Open a new connection to a SQLite database.
Connection::open(path)
is equivalent to Connection::open_with_flags(path, SQLITE_OPEN_READ_WRITE | SQLITE_OPEN_CREATE)
.
Failure
Will return Err
if path
cannot be converted to a C-compatible string or if the
underlying SQLite open call fails.
fn open_in_memory() -> Result<Connection>
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Open a new connection to an in-memory SQLite database.
Failure
Will return Err
if the underlying SQLite open call fails.
fn open_with_flags<P: AsRef<Path>>(
path: P,
flags: OpenFlags
) -> Result<Connection>
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path: P,
flags: OpenFlags
) -> Result<Connection>
Open a new connection to a SQLite database.
Database Connection for a description of valid flag combinations.
Failure
Will return Err
if path
cannot be converted to a C-compatible string or if the
underlying SQLite open call fails.
fn open_in_memory_with_flags(flags: OpenFlags) -> Result<Connection>
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Open a new connection to an in-memory SQLite database.
Database Connection for a description of valid flag combinations.
Failure
Will return Err
if the underlying SQLite open call fails.
fn execute_batch(&self, sql: &str) -> Result<()>
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Convenience method to run multiple SQL statements (that cannot take any parameters).
Uses sqlite3_exec under the hood.
Example
fn create_tables(conn: &Connection) -> Result<()> { conn.execute_batch("BEGIN; CREATE TABLE foo(x INTEGER); CREATE TABLE bar(y TEXT); COMMIT;") }
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn execute(&self, sql: &str, params: &[&ToSql]) -> Result<c_int>
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Convenience method to prepare and execute a single SQL statement.
On success, returns the number of rows that were changed or inserted or deleted (via
sqlite3_changes
).
Example
fn update_rows(conn: &Connection) { match conn.execute("UPDATE foo SET bar = 'baz' WHERE qux = ?", &[&1i32]) { Ok(updated) => println!("{} rows were updated", updated), Err(err) => println!("update failed: {}", err), } }
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn execute_named(&self, sql: &str, params: &[(&str, &ToSql)]) -> Result<c_int>
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Convenience method to prepare and execute a single SQL statement with named parameter(s).
On success, returns the number of rows that were changed or inserted or deleted (via
sqlite3_changes
).
Example
fn insert(conn: &Connection) -> Result<i32> { conn.execute_named("INSERT INTO test (name) VALUES (:name)", &[(":name", &"one")]) }
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn last_insert_rowid(&self) -> i64
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Get the SQLite rowid of the most recent successful INSERT.
Uses sqlite3_last_insert_rowid under the hood.
fn query_row<T, F>(&self, sql: &str, params: &[&ToSql], f: F) -> Result<T> where
F: FnOnce(&Row) -> T,
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F: FnOnce(&Row) -> T,
Convenience method to execute a query that is expected to return a single row.
Example
fn preferred_locale(conn: &Connection) -> Result<String> { conn.query_row("SELECT value FROM preferences WHERE name='locale'", &[], |row| { row.get(0) }) }
If the query returns more than one row, all rows except the first are ignored.
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn query_row_named<T, F>(
&self,
sql: &str,
params: &[(&str, &ToSql)],
f: F
) -> Result<T> where
F: FnOnce(&Row) -> T,
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&self,
sql: &str,
params: &[(&str, &ToSql)],
f: F
) -> Result<T> where
F: FnOnce(&Row) -> T,
Convenience method to execute a query with named parameter(s) that is expected to return a single row.
If the query returns more than one row, all rows except the first are ignored.
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn query_row_and_then<T, E, F>(
&self,
sql: &str,
params: &[&ToSql],
f: F
) -> Result<T, E> where
F: FnOnce(&Row) -> Result<T, E>,
E: From<Error>,
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&self,
sql: &str,
params: &[&ToSql],
f: F
) -> Result<T, E> where
F: FnOnce(&Row) -> Result<T, E>,
E: From<Error>,
Convenience method to execute a query that is expected to return a single row,
and execute a mapping via f
on that returned row with the possibility of failure.
The Result
type of f
must implement std::convert::From<Error>
.
Example
fn preferred_locale(conn: &Connection) -> Result<String> { conn.query_row_and_then("SELECT value FROM preferences WHERE name='locale'", &[], |row| { row.get_checked(0) }) }
If the query returns more than one row, all rows except the first are ignored.
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn query_row_safe<T, F>(&self, sql: &str, params: &[&ToSql], f: F) -> Result<T> where
F: FnOnce(&Row) -> T,
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F: FnOnce(&Row) -> T,
: Use query_row instead
Convenience method to execute a query that is expected to return a single row.
Example
fn preferred_locale(conn: &Connection) -> Result<String> { conn.query_row_safe("SELECT value FROM preferences WHERE name='locale'", &[], |row| { row.get(0) }) }
If the query returns more than one row, all rows except the first are ignored.
Deprecated
This method should be considered deprecated. Use query_row
instead, which now
does exactly the same thing.
fn prepare<'a>(&'a self, sql: &str) -> Result<Statement<'a>>
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Prepare a SQL statement for execution.
Example
fn insert_new_people(conn: &Connection) -> Result<()> { let mut stmt = try!(conn.prepare("INSERT INTO People (name) VALUES (?)")); try!(stmt.execute(&[&"Joe Smith"])); try!(stmt.execute(&[&"Bob Jones"])); Ok(()) }
Failure
Will return Err
if sql
cannot be converted to a C-compatible string or if the
underlying SQLite call fails.
fn close(self) -> Result<(), (Connection, Error)>
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Close the SQLite connection.
This is functionally equivalent to the Drop
implementation for Connection
except
that on failure, it returns an error and the connection itself (presumably so closing
can be attempted again).
Failure
Will return Err
if the underlying SQLite call fails.
fn load_extension_enable(&self) -> Result<()>
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Enable loading of SQLite extensions. Strongly consider using LoadExtensionGuard
instead of this function.
Example
fn load_my_extension(conn: &Connection) -> Result<()> { try!(conn.load_extension_enable()); try!(conn.load_extension(Path::new("my_sqlite_extension"), None)); conn.load_extension_disable() }
Failure
Will return Err
if the underlying SQLite call fails.
fn load_extension_disable(&self) -> Result<()>
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Disable loading of SQLite extensions.
See load_extension_enable
for an example.
Failure
Will return Err
if the underlying SQLite call fails.
fn load_extension<P: AsRef<Path>>(
&self,
dylib_path: P,
entry_point: Option<&str>
) -> Result<()>
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&self,
dylib_path: P,
entry_point: Option<&str>
) -> Result<()>
Load the SQLite extension at dylib_path
. dylib_path
is passed through to
sqlite3_load_extension
, which may attempt OS-specific modifications if the file
cannot be loaded directly.
If entry_point
is None
, SQLite will attempt to find the entry point. If it is not
None
, the entry point will be passed through to sqlite3_load_extension
.
Example
fn load_my_extension(conn: &Connection) -> Result<()> { let _guard = try!(LoadExtensionGuard::new(conn)); conn.load_extension("my_sqlite_extension", None) }
Failure
Will return Err
if the underlying SQLite call fails.
unsafe fn handle(&self) -> *mut sqlite3
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Get access to the underlying SQLite database connection handle.
Warning
You should not need to use this function. If you do need to, please open an issue
on the rusqlite repository and describe
your use case. This function is unsafe because it gives you raw access to the SQLite
connection, and what you do with it could impact the safety of this Connection
.