Question

更新＃1 我有一个php文件，其中有多个查询可以创建多个csv文件。我想结合查询。

我的mysql table有5列：ID，货币，汇率，日期，临时值

创建表table并插入一些记录

    CREATE TABLE IF NOT EXISTS `table` ( `id` INT NOT NULL AUTO_INCREMENT , `currency` VARCHAR(254) NOT NULL , `rate` FLOAT NOT NULL , `date` VARCHAR(254) NOT NULL , `temptime` DATE NOT NULL , PRIMARY KEY (`id`), UNIQUE `UNIQUE` (`currency`, `temptime`)) ENGINE = MyISAM;

INSERT INTO `table` 
(currency, rate, date, temptime)
VALUES 
('USD', '1.232', '1521212400', '2018-03-16'),
('USD', '1.258', '1521126000', '2018-03-15'),
('JPY', '133.82', '1521212400', '2018-03-16'),
('JPY', '131.88', '1521126000', '2018-03-15'),
('EUR', '1.99', '1521212400', '2018-03-16'),
('EUR', '1.85', '1521126000', '2018-03-15'),
('BRL', '1.6654', '1521212400', '2018-03-16'),
('BRL', '1.5498', '1521126000', '2018-03-15'),
('ZAR', '1.99654', '1521212400', '2018-03-16'),
('ZAR', '2.0198', '1521126000', '2018-03-15'),
('RUB', '19.9654', '1521212400', '2018-03-16'),
('RUB', '20.0198', '1521126000', '2018-03-15');

这是我想要为列＆＃34;货币＆＃34;组合的2个查询。美元和欧元：

    $result = mysql_query("SELECT temptime, rate FROM `table` WHERE currency='USD' ORDER BY date asc"); 
if (!$result) die('Couldn\'t fetch records'); 
$num_fields = mysql_num_fields($result); 
$headers = array(); 
for ($i = 0; $i < $num_fields; $i++) 
{     
       $headers[] = mysql_field_name($result , $i); 
} 
$fp = fopen('csv/USD.csv', 'w'); 


if ($fp && $result) 
{     
       fputcsv($fp, $headers); 
       while ($row = mysql_fetch_row($result)) 
       {
          fputcsv($fp, array_values($row)); 
       }
} 

$result = mysql_query("SELECT temptime, rate FROM `table` WHERE currency='EUR' ORDER BY date asc"); 
if (!$result) die('Couldn\'t fetch records'); 
$num_fields = mysql_num_fields($result); 
$headers = array(); 
for ($i = 0; $i < $num_fields; $i++) 
{     
       $headers[] = mysql_field_name($result , $i); 
} 
$fp = fopen('csv/EUR.csv', 'w'); 


if ($fp && $result) 
{     
       fputcsv($fp, $headers); 
       while ($row = mysql_fetch_row($result)) 
       {
          fputcsv($fp, array_values($row)); 
       }
}

谢谢

Answer 1

您可以使用每行中的货币字段来决定要写入哪个文件，我已经使用了一个文件句柄数组，而不是围绕哪个文件有任何条件，您只需使用该货币作为索引即可文件句柄......

// Create an array of files, each associated with currency
$fp = array( 'EUR' => fopen('csv/EUR.csv', 'w'),
        'USD' => fopen('csv/USD.csv', 'w'));

$result = mysql_query("SELECT currency, temptime, rate FROM `table` ORDER BY date asc");
if (!$result) die("Couldn't fetch records");
$num_fields = mysql_num_fields($result);
$headers = array();
for ($i = 0; $i < $num_fields; $i++)
{
    $headers[] = mysql_field_name($result , $i);
}
// Write out headers to each file.
foreach ( $fp as $output )  {
    fputcsv($output, $headers);
}

while ($row = mysql_fetch_row($result))     {
    // Use first field to decide which file to write to.
    $currency = array_shift($row);
    fputcsv($fp[$currency], $row);
}
// Close all of the files.
foreach ( $fp as $output )  {
    fclose($output);
}

由于我没有您的数据库，我无法对此进行测试，但如果您有任何问题，请告知我们。

Answer 2

还考虑不使用循环并直接从MySQL导出到CSV SELECT ... INTO OUTFILE（LOAD DATA INFILE的补充）。

具体来说，在PHP下面单独执行两个动作查询（确保转义引号）。虽然没有结合，但这个过程应该是比多个循环更快的读/写IO过程。另外，您可以在不更改csv导出代码的情况下交换应用层（即使用Python，Java）！

SELECT temptime, rate 
INTO OUTFILE '/path/to/csv/USD.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
FROM `table` 
WHERE currency='USD' 
ORDER BY `date` asc;

SELECT temptime, rate 
INTO OUTFILE '/path/to/csv/EUR.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
FROM `table` 
WHERE currency='EUR' 
ORDER BY `date` asc;

对于一个调用，将它们放在MySQL存储过程中：

DELIMITER $$
DROP PROCEDURE IF EXISTS export_csv$$

CREATE PROCEDURE export_csv
BEGIN
    -- SELECT ... INTO OUTFILE COMMANDS
END$$

DELIMITER ;

然后在PHP中使用单行（使用mysqli API）运行它：

$result = mysqli_query($conn, "CALL export_csv")

请注意：标题不会与上述命令一起传递。使用需要类型转换的联合解决调整查询。并且CSV不会存储类型或unicodes元数据以在此处出现问题。

SELECT 'temptime' as col1, 'rate' as col2
UNION ALL
SELECT CAST(temptime, CHAR(10) as col1, 
       CAST(ROUND(rate,4) AS CHAR(3)) as col2
INTO OUTFILE '/path/to/csv/USD.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
FROM `table` 
WHERE currency='USD' ;

Php从一个mysql查询创建多个csv（s）文件

2 个答案: