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#
# Nim's Runtime Library
# (c) Copyright 2012 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## A higher level `SQLite`:idx: database wrapper. This interface
## is implemented for other databases too.
##
## Example:
##
## .. code-block:: nim
##
## import db_sqlite, math
##
## let theDb = open("mytest.db", nil, nil, nil)
##
## theDb.exec(sql"Drop table if exists myTestTbl")
## theDb.exec(sql("""create table myTestTbl (
## Id INTEGER PRIMARY KEY,
## Name VARCHAR(50) NOT NULL,
## i INT(11),
## f DECIMAL(18,10))"""))
##
## theDb.exec(sql"BEGIN")
## for i in 1..1000:
## theDb.exec(sql"INSERT INTO myTestTbl (name,i,f) VALUES (?,?,?)",
## "Item#" & $i, i, sqrt(i.float))
## theDb.exec(sql"COMMIT")
##
## for x in theDb.fastRows(sql"select * from myTestTbl"):
## echo x
##
## let id = theDb.tryInsertId(sql"INSERT INTO myTestTbl (name,i,f) VALUES (?,?,?)",
## "Item#1001", 1001, sqrt(1001.0))
## echo "Inserted item: ", theDb.getValue(sql"SELECT name FROM myTestTbl WHERE id=?", id)
##
## theDb.close()
import strutils, sqlite3
type
DbConn* = PSqlite3 ## encapsulates a database connection
Row* = seq[string] ## a row of a dataset. NULL database values will be
## transformed always to the empty string.
InstantRow* = Pstmt ## a handle that can be used to get a row's column
## text on demand
EDb* = object of IOError ## exception that is raised if a database error occurs
SqlQuery* = distinct string ## an SQL query string
FDb* = object of IOEffect ## effect that denotes a database operation
FReadDb* = object of FDb ## effect that denotes a read operation
FWriteDb* = object of FDb ## effect that denotes a write operation
{.deprecated: [TRow: Row, TSqlQuery: SqlQuery, TDbConn: DbConn].}
proc sql*(query: string): SqlQuery {.noSideEffect, inline.} =
## constructs a SqlQuery from the string `query`. This is supposed to be
## used as a raw-string-literal modifier:
## ``sql"update user set counter = counter + 1"``
##
## If assertions are turned off, it does nothing. If assertions are turned
## on, later versions will check the string for valid syntax.
result = SqlQuery(query)
proc dbError(db: DbConn) {.noreturn.} =
## raises an EDb exception.
var e: ref EDb
new(e)
e.msg = $sqlite3.errmsg(db)
raise e
proc dbError*(msg: string) {.noreturn.} =
## raises an EDb exception with message `msg`.
var e: ref EDb
new(e)
e.msg = msg
raise e
proc dbQuote(s: string): string =
if s.isNil: return "NULL"
result = "'"
for c in items(s):
if c == '\'': add(result, "''")
else: add(result, c)
add(result, '\'')
proc dbFormat(formatstr: SqlQuery, args: varargs[string]): string =
result = ""
var a = 0
for c in items(string(formatstr)):
if c == '?':
add(result, dbQuote(args[a]))
inc(a)
else:
add(result, c)
proc tryExec*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): bool {.tags: [FReadDb, FWriteDb].} =
## tries to execute the query and returns true if successful, false otherwise.
var q = dbFormat(query, args)
var stmt: sqlite3.Pstmt
if prepare_v2(db, q, q.len.cint, stmt, nil) == SQLITE_OK:
if step(stmt) == SQLITE_DONE:
result = finalize(stmt) == SQLITE_OK
proc exec*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]) {.
tags: [FReadDb, FWriteDb].} =
## executes the query and raises EDB if not successful.
if not tryExec(db, query, args): dbError(db)
proc newRow(L: int): Row =
newSeq(result, L)
for i in 0..L-1: result[i] = ""
proc setupQuery(db: DbConn, query: SqlQuery,
args: varargs[string]): Pstmt =
var q = dbFormat(query, args)
if prepare_v2(db, q, q.len.cint, result, nil) != SQLITE_OK: dbError(db)
proc setRow(stmt: Pstmt, r: var Row, cols: cint) =
for col in 0..cols-1:
setLen(r[col], column_bytes(stmt, col)) # set capacity
setLen(r[col], 0)
let x = column_text(stmt, col)
if not isNil(x): add(r[col], x)
iterator fastRows*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): Row {.tags: [FReadDb].} =
## Executes the query and iterates over the result dataset.
##
## This is very fast, but potentially dangerous. Use this iterator only
## if you require **ALL** the rows.
##
## Breaking the fastRows() iterator during a loop will cause the next
## database query to raise an [EDb] exception ``unable to close due to ...``.
var stmt = setupQuery(db, query, args)
var L = (column_count(stmt))
var result = newRow(L)
while step(stmt) == SQLITE_ROW:
setRow(stmt, result, L)
yield result
if finalize(stmt) != SQLITE_OK: dbError(db)
iterator instantRows*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): InstantRow
{.tags: [FReadDb].} =
## same as fastRows but returns a handle that can be used to get column text
## on demand using []. Returned handle is valid only within the interator body.
var stmt = setupQuery(db, query, args)
while step(stmt) == SQLITE_ROW:
yield stmt
if finalize(stmt) != SQLITE_OK: dbError(db)
proc `[]`*(row: InstantRow, col: int32): string {.inline.} =
## returns text for given column of the row
$column_text(row, col)
proc len*(row: InstantRow): int32 {.inline.} =
## returns number of columns in the row
column_count(row)
proc getRow*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): Row {.tags: [FReadDb].} =
## retrieves a single row. If the query doesn't return any rows, this proc
## will return a Row with empty strings for each column.
var stmt = setupQuery(db, query, args)
var L = (column_count(stmt))
result = newRow(L)
if step(stmt) == SQLITE_ROW:
setRow(stmt, result, L)
if finalize(stmt) != SQLITE_OK: dbError(db)
proc getAllRows*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): seq[Row] {.tags: [FReadDb].} =
## executes the query and returns the whole result dataset.
result = @[]
for r in fastRows(db, query, args):
result.add(r)
iterator rows*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): Row {.tags: [FReadDb].} =
## same as `FastRows`, but slower and safe.
for r in fastRows(db, query, args): yield r
proc getValue*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): string {.tags: [FReadDb].} =
## executes the query and returns the first column of the first row of the
## result dataset. Returns "" if the dataset contains no rows or the database
## value is NULL.
var stmt = setupQuery(db, query, args)
if step(stmt) == SQLITE_ROW:
let cb = column_bytes(stmt, 0)
if cb == 0:
result = ""
else:
result = newStringOfCap(cb)
add(result, column_text(stmt, 0))
else:
result = ""
if finalize(stmt) != SQLITE_OK: dbError(db)
proc tryInsertID*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): int64
{.tags: [FWriteDb], raises: [].} =
## executes the query (typically "INSERT") and returns the
## generated ID for the row or -1 in case of an error.
var q = dbFormat(query, args)
var stmt: sqlite3.Pstmt
result = -1
if prepare_v2(db, q, q.len.cint, stmt, nil) == SQLITE_OK:
if step(stmt) == SQLITE_DONE:
result = last_insert_rowid(db)
if finalize(stmt) != SQLITE_OK:
result = -1
proc insertID*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
## executes the query (typically "INSERT") and returns the
## generated ID for the row. For Postgre this adds
## ``RETURNING id`` to the query, so it only works if your primary key is
## named ``id``.
result = tryInsertID(db, query, args)
if result < 0: dbError(db)
proc execAffectedRows*(db: DbConn, query: SqlQuery,
args: varargs[string, `$`]): int64 {.
tags: [FReadDb, FWriteDb].} =
## executes the query (typically "UPDATE") and returns the
## number of affected rows.
exec(db, query, args)
result = changes(db)
proc close*(db: DbConn) {.tags: [FDb].} =
## closes the database connection.
if sqlite3.close(db) != SQLITE_OK: dbError(db)
proc open*(connection, user, password, database: string): DbConn {.
tags: [FDb].} =
## opens a database connection. Raises `EDb` if the connection could not
## be established. Only the ``connection`` parameter is used for ``sqlite``.
var db: DbConn
if sqlite3.open(connection, db) == SQLITE_OK:
result = db
else:
dbError(db)
proc setEncoding*(connection: DbConn, encoding: string): bool {.
tags: [FDb].} =
## sets the encoding of a database connection, returns true for
## success, false for failure.
##
## Note that the encoding cannot be changed once it's been set.
## According to SQLite3 documentation, any attempt to change
## the encoding after the database is created will be silently
## ignored.
exec(connection, sql"PRAGMA encoding = ?", [encoding])
result = connection.getValue(sql"PRAGMA encoding") == encoding
when not defined(testing) and isMainModule:
var db = open("db.sql", "", "", "")
exec(db, sql"create table tbl1(one varchar(10), two smallint)", [])
exec(db, sql"insert into tbl1 values('hello!',10)", [])
exec(db, sql"insert into tbl1 values('goodbye', 20)", [])
#db.query("create table tbl1(one varchar(10), two smallint)")
#db.query("insert into tbl1 values('hello!',10)")
#db.query("insert into tbl1 values('goodbye', 20)")
for r in db.rows(sql"select * from tbl1", []):
echo(r[0], r[1])
for r in db.instantRows(sql"select * from tbl1", []):
echo(r[0], r[1])
db_sqlite.close(db)