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298 lines
9.9 KiB
Nim
298 lines
9.9 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 `mySQL`:idx: database wrapper. The same interface is
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## implemented for other databases too.
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##
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## Example:
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##
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## .. code-block:: Nim
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##
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## import db_mysql, math
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##
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## let theDb = open("localhost", "nim", "nim", "test")
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##
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## theDb.exec(sql"Drop table if exists myTestTbl")
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## theDb.exec(sql("create table myTestTbl (" &
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## " Id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY, " &
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## " Name VARCHAR(50) NOT NULL, " &
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## " i INT(11), " &
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## " f DECIMAL(18,10))"))
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##
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## theDb.exec(sql"START TRANSACTION")
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## for i in 1..1000:
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## theDb.exec(sql"INSERT INTO myTestTbl (name,i,f) VALUES (?,?,?)",
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## "Item#" & $i, i, sqrt(i.float))
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## theDb.exec(sql"COMMIT")
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##
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## for x in theDb.fastRows(sql"select * from myTestTbl"):
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## echo x
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##
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## let id = theDb.tryInsertId(sql"INSERT INTO myTestTbl (name,i,f) VALUES (?,?,?)",
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## "Item#1001", 1001, sqrt(1001.0))
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## echo "Inserted item: ", theDb.getValue(sql"SELECT name FROM myTestTbl WHERE id=?", id)
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##
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## theDb.close()
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import strutils, mysql
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type
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DbConn* = PMySQL ## encapsulates a database connection
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Row* = 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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InstantRow* = tuple[row: cstringArray, len: int] ## a handle that can be
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## used to get a row's
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## column text on demand
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EDb* = object of IOError ## exception that is raised if a database error occurs
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SqlQuery* = 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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{.deprecated: [TRow: Row, TSqlQuery: SqlQuery, TDbConn: DbConn].}
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proc sql*(query: string): SqlQuery {.noSideEffect, inline.} =
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## constructs a SqlQuery 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 = SqlQuery(query)
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proc dbError(db: DbConn) {.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 = $mysql.error(db)
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raise e
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proc dbError*(msg: string) {.noreturn.} =
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## raises an EDb exception with message `msg`.
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var e: ref EDb
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new(e)
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e.msg = msg
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raise e
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when false:
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proc dbQueryOpt*(db: DbConn, query: string, args: varargs[string, `$`]) =
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var stmt = mysql_stmt_init(db)
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if stmt == nil: dbError(db)
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if mysql_stmt_prepare(stmt, query, len(query)) != 0:
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dbError(db)
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var
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binding: seq[MYSQL_BIND]
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discard mysql_stmt_close(stmt)
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proc dbQuote*(s: string): string =
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## DB quotes the string.
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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: SqlQuery, 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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if args[a] == nil:
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add(result, "NULL")
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else:
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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: DbConn, query: SqlQuery, args: varargs[string, `$`]): bool {.
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tags: [FReadDB, FWriteDb].} =
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## tries to execute the query and returns true if successful, false otherwise.
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var q = dbFormat(query, args)
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return mysql.realQuery(db, q, q.len) == 0'i32
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proc rawExec(db: DbConn, query: SqlQuery, args: varargs[string, `$`]) =
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var q = dbFormat(query, args)
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if mysql.realQuery(db, q, q.len) != 0'i32: dbError(db)
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proc exec*(db: DbConn, query: SqlQuery, args: varargs[string, `$`]) {.
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tags: [FReadDB, FWriteDb].} =
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## executes the query and raises EDB if not successful.
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var q = dbFormat(query, args)
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if mysql.realQuery(db, q, q.len) != 0'i32: dbError(db)
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proc newRow(L: int): Row =
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newSeq(result, L)
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for i in 0..L-1: result[i] = ""
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proc properFreeResult(sqlres: mysql.PRES, row: cstringArray) =
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if row != nil:
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while mysql.fetchRow(sqlres) != nil: discard
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mysql.freeResult(sqlres)
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iterator fastRows*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): Row {.tags: [FReadDB].} =
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## executes the query and iterates over the result dataset.
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##
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## This is very fast, but potentially dangerous. Use this iterator only
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## if you require **ALL** the rows.
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##
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## Breaking the fastRows() iterator during a loop will cause the next
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## database query to raise an [EDb] exception ``Commands out of sync``.
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rawExec(db, query, args)
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var sqlres = mysql.useResult(db)
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if sqlres != nil:
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var L = int(mysql.numFields(sqlres))
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var result = newRow(L)
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var row: cstringArray
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while true:
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row = mysql.fetchRow(sqlres)
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if row == nil: break
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for i in 0..L-1:
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setLen(result[i], 0)
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if row[i] == nil:
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result[i] = nil
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else:
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add(result[i], row[i])
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yield result
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properFreeResult(sqlres, row)
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iterator instantRows*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): InstantRow
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{.tags: [FReadDb].} =
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## same as fastRows but returns a handle that can be used to get column text
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## on demand using []. Returned handle is valid only within the interator body.
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rawExec(db, query, args)
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var sqlres = mysql.useResult(db)
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if sqlres != nil:
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let L = int(mysql.numFields(sqlres))
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var row: cstringArray
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while true:
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row = mysql.fetchRow(sqlres)
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if row == nil: break
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yield (row: row, len: L)
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properFreeResult(sqlres, row)
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proc `[]`*(row: InstantRow, col: int): string {.inline.} =
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## returns text for given column of the row
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$row.row[col]
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proc len*(row: InstantRow): int {.inline.} =
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## returns number of columns in the row
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row.len
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proc getRow*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): Row {.tags: [FReadDB].} =
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## retrieves a single row. If the query doesn't return any rows, this proc
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## will return a Row with empty strings for each column.
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rawExec(db, query, args)
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var sqlres = mysql.useResult(db)
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if sqlres != nil:
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var L = int(mysql.numFields(sqlres))
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result = newRow(L)
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var row = mysql.fetchRow(sqlres)
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if row != nil:
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for i in 0..L-1:
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setLen(result[i], 0)
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if row[i] == nil:
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result[i] = nil
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else:
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add(result[i], row[i])
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properFreeResult(sqlres, row)
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proc getAllRows*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): seq[Row] {.tags: [FReadDB].} =
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## executes the query and returns the whole result dataset.
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result = @[]
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rawExec(db, query, args)
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var sqlres = mysql.useResult(db)
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if sqlres != nil:
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var L = int(mysql.numFields(sqlres))
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var row: cstringArray
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var j = 0
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while true:
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row = mysql.fetchRow(sqlres)
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if row == nil: break
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setLen(result, j+1)
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newSeq(result[j], L)
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for i in 0..L-1:
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if row[i] == nil:
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result[j][i] = nil
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else:
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result[j][i] = $row[i]
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inc(j)
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mysql.freeResult(sqlres)
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iterator rows*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): Row {.tags: [FReadDB].} =
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## same as `fastRows`, but slower and safe.
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for r in items(getAllRows(db, query, args)): yield r
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proc getValue*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): string {.tags: [FReadDB].} =
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## executes the query and returns the first column of the first row of the
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## result dataset. Returns "" if the dataset contains no rows or the database
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## value is NULL.
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result = getRow(db, query, args)[0]
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proc tryInsertId*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
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## executes the query (typically "INSERT") and returns the
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## generated ID for the row or -1 in case of an error.
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var q = dbFormat(query, args)
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if mysql.realQuery(db, q, q.len) != 0'i32:
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result = -1'i64
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else:
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result = mysql.insertId(db)
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proc insertId*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): int64 {.tags: [FWriteDb].} =
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## executes the query (typically "INSERT") and returns the
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## generated ID for the row.
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result = tryInsertID(db, query, args)
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if result < 0: dbError(db)
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proc execAffectedRows*(db: DbConn, query: SqlQuery,
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args: varargs[string, `$`]): int64 {.
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tags: [FReadDB, FWriteDb].} =
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## runs the query (typically "UPDATE") and returns the
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## number of affected rows
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rawExec(db, query, args)
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result = mysql.affectedRows(db)
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proc close*(db: DbConn) {.tags: [FDb].} =
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## closes the database connection.
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if db != nil: mysql.close(db)
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proc open*(connection, user, password, database: string): DbConn {.
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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.
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result = mysql.init(nil)
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if result == nil: dbError("could not open database connection")
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let
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colonPos = connection.find(':')
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host = if colonPos < 0: connection
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else: substr(connection, 0, colonPos-1)
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port: int32 = if colonPos < 0: 0'i32
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else: substr(connection, colonPos+1).parseInt.int32
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if mysql.realConnect(result, host, user, password, database,
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port, nil, 0) == nil:
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var errmsg = $mysql.error(result)
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db_mysql.close(result)
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dbError(errmsg)
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proc setEncoding*(connection: DbConn, encoding: string): bool {.
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tags: [FDb].} =
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## sets the encoding of a database connection, returns true for
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## success, false for failure.
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result = mysql.set_character_set(connection, encoding) == 0
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