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208 lines
7.3 KiB
Nim
208 lines
7.3 KiB
Nim
#
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#
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# Nim's Runtime Library
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# (c) Copyright 2012 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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## A higher level `SQLite`:idx: database wrapper. This interface
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## is implemented for other databases too.
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import strutils, sqlite3
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type
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TDbConn* = PSqlite3 ## encapsulates a database connection
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TRow* = seq[string] ## a row of a dataset. NULL database values will be
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## transformed always to the empty string.
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EDb* = object of IOError ## exception that is raised if a database error occurs
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TSqlQuery* = distinct string ## an SQL query string
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FDb* = object of IOEffect ## effect that denotes a database operation
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FReadDb* = object of FDb ## effect that denotes a read operation
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FWriteDb* = object of FDb ## effect that denotes a write operation
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proc sql*(query: string): TSqlQuery {.noSideEffect, inline.} =
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## constructs a TSqlQuery from the string `query`. This is supposed to be
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## used as a raw-string-literal modifier:
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## ``sql"update user set counter = counter + 1"``
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##
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## If assertions are turned off, it does nothing. If assertions are turned
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## on, later versions will check the string for valid syntax.
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result = TSqlQuery(query)
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proc dbError(db: TDbConn) {.noreturn.} =
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## raises an EDb exception.
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var e: ref EDb
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new(e)
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e.msg = $sqlite3.errmsg(db)
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raise e
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proc dbError*(msg: string) {.noreturn.} =
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## raises an EDb exception with message `msg`.
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var e: ref EDb
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new(e)
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e.msg = msg
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raise e
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proc dbQuote(s: string): string =
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if s.isNil: return "NULL"
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result = "'"
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for c in items(s):
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if c == '\'': add(result, "''")
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else: add(result, c)
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add(result, '\'')
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proc dbFormat(formatstr: TSqlQuery, args: varargs[string]): string =
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result = ""
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var a = 0
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for c in items(string(formatstr)):
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if c == '?':
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add(result, dbQuote(args[a]))
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inc(a)
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else:
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add(result, c)
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proc tryExec*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): bool {.tags: [FReadDb, FWriteDb].} =
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## tries to execute the query and returns true if successful, false otherwise.
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var q = dbFormat(query, args)
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var stmt: sqlite3.Pstmt
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if prepare_v2(db, q, q.len.cint, stmt, nil) == SQLITE_OK:
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if step(stmt) == SQLITE_DONE:
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result = finalize(stmt) == SQLITE_OK
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proc exec*(db: TDbConn, query: TSqlQuery, args: varargs[string, `$`]) {.
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tags: [FReadDb, FWriteDb].} =
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## executes the query and raises EDB if not successful.
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if not tryExec(db, query, args): dbError(db)
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proc newRow(L: int): TRow =
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newSeq(result, L)
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for i in 0..L-1: result[i] = ""
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proc setupQuery(db: TDbConn, query: TSqlQuery,
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args: varargs[string]): Pstmt =
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var q = dbFormat(query, args)
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if prepare_v2(db, q, q.len.cint, result, nil) != SQLITE_OK: dbError(db)
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proc setRow(stmt: Pstmt, r: var TRow, cols: cint) =
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for col in 0..cols-1:
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setLen(r[col], column_bytes(stmt, col)) # set capacity
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setLen(r[col], 0)
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let x = column_text(stmt, col)
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if not isNil(x): add(r[col], x)
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iterator fastRows*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): TRow {.tags: [FReadDb].} =
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## executes the query and iterates over the result dataset. This is very
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## fast, but potenially dangerous: If the for-loop-body executes another
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## query, the results can be undefined. For Sqlite it is safe though.
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var stmt = setupQuery(db, query, args)
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var L = (column_count(stmt))
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var result = newRow(L)
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while step(stmt) == SQLITE_ROW:
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setRow(stmt, result, L)
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yield result
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if finalize(stmt) != SQLITE_OK: dbError(db)
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proc getRow*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): TRow {.tags: [FReadDb].} =
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## retrieves a single row. If the query doesn't return any rows, this proc
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## will return a TRow with empty strings for each column.
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var stmt = setupQuery(db, query, args)
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var L = (column_count(stmt))
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result = newRow(L)
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if step(stmt) == SQLITE_ROW:
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setRow(stmt, result, L)
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if finalize(stmt) != SQLITE_OK: dbError(db)
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proc getAllRows*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): seq[TRow] {.tags: [FReadDb].} =
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## executes the query and returns the whole result dataset.
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result = @[]
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for r in fastRows(db, query, args):
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result.add(r)
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iterator rows*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): TRow {.tags: [FReadDb].} =
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## same as `FastRows`, but slower and safe.
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for r in fastRows(db, query, args): yield r
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proc getValue*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): string {.tags: [FReadDb].} =
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## executes the query and returns the first column of the first row of the
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## result dataset. Returns "" if the dataset contains no rows or the database
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## value is NULL.
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var stmt = setupQuery(db, query, args)
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if step(stmt) == SQLITE_ROW:
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let cb = column_bytes(stmt, 0)
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if cb == 0:
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result = ""
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else:
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result = newStringOfCap(cb)
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add(result, column_text(stmt, 0))
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else:
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result = ""
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if finalize(stmt) != SQLITE_OK: dbError(db)
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proc tryInsertID*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): int64
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{.tags: [FWriteDb], raises: [].} =
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## executes the query (typically "INSERT") and returns the
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## generated ID for the row or -1 in case of an error.
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var q = dbFormat(query, args)
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var stmt: sqlite3.Pstmt
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result = -1
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if prepare_v2(db, q, q.len.cint, stmt, nil) == SQLITE_OK:
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if step(stmt) == SQLITE_DONE:
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result = last_insert_rowid(db)
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if finalize(stmt) != SQLITE_OK:
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result = -1
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proc insertID*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
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## executes the query (typically "INSERT") and returns the
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## generated ID for the row. For Postgre this adds
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## ``RETURNING id`` to the query, so it only works if your primary key is
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## named ``id``.
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result = tryInsertID(db, query, args)
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if result < 0: dbError(db)
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proc execAffectedRows*(db: TDbConn, query: TSqlQuery,
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args: varargs[string, `$`]): int64 {.
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tags: [FReadDb, FWriteDb].} =
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## executes the query (typically "UPDATE") and returns the
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## number of affected rows.
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exec(db, query, args)
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result = changes(db)
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proc close*(db: TDbConn) {.tags: [FDb].} =
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## closes the database connection.
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if sqlite3.close(db) != SQLITE_OK: dbError(db)
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proc open*(connection, user, password, database: string): TDbConn {.
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tags: [FDb].} =
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## opens a database connection. Raises `EDb` if the connection could not
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## be established. Only the ``connection`` parameter is used for ``sqlite``.
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var db: TDbConn
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if sqlite3.open(connection, db) == SQLITE_OK:
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result = db
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else:
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dbError(db)
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when isMainModule:
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var db = open("db.sql", "", "", "")
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exec(db, sql"create table tbl1(one varchar(10), two smallint)", [])
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exec(db, sql"insert into tbl1 values('hello!',10)", [])
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exec(db, sql"insert into tbl1 values('goodbye', 20)", [])
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#db.query("create table tbl1(one varchar(10), two smallint)")
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#db.query("insert into tbl1 values('hello!',10)")
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#db.query("insert into tbl1 values('goodbye', 20)")
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for r in db.rows(sql"select * from tbl1", []):
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echo(r[0], r[1])
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db_sqlite.close(db)
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