我正在尝试为以下任务重新激活我的PHP知识： 我有一个更大的文本文件，其中包含未分隔的逗号分隔信息行，每个值都用'“'括起来。 每一行都可以理解为一个数据集，该行的第一个值告诉我该行属于哪个表。
现在我需要读取文件，对行进行排序（以便属于同一个表的行在一起），检测不同的块并将它们保存在单独的文本文件中。之后，我可以使用来自infile的加载数据快速导入到mysql数据库中。
所以，我可以通过这个打开文件并对行进行排序：
<?php
$lines = file("importfile_unsorted.txt");
natsort($lines);
file_put_contents("importfile_sorted.txt", implode($lines));
?>
这很有效。但现在我被困了。 importfile_sorted.txt如下所示：
"AV1","0","0","0","0","0","0","0","0","0","0","0:0","0:0","0:0"
"AV2","0","0","0","0","0","0","0","0","0","0","0:0","0:0","0:0"
.... [这将是第一个块，所有这些行都应保存在“av.txt”中 在下一行中，新块“F”以几行开头：
"F1","D","D","Deutsch",,,"0","W"
"F4","E","E","Englisch",,,"0","W"
"F7","K","K","Kath.Religionslehre",,,"0","W"
"F8","Ev","Ev","Evang.Religionslehre",,,"0","W"
"F9","Eth","Eth","Ethik",,,"0","W"
... [将所有这些以Fxx开头的行保存到文件f.txt并转到下一个块]
"G1","PhL","PÜG"
"G2","ChL","ChÜ"
...
"K1","5a","5a",,"304","Ma","Wei","0","16","16","5",,,,,"1","1","0",,"0","0","0","0"
"K2","5b","5b",,"303","Wo","Hm","0","32","16","5",,,,,"1","1","0",,"0","0","0","0"
"K3","5c","5c",,"302","Gr","Ro","0","32","16","5",,,,,"1","1","0",,"0","0","0","0"
......等等。之后，有一些块具有固定的第一列，如下所示：
"PL","Di 1","Ba","Q12","Inf1","CoR1"
"PL","Di 1","Bb","Q12","F","Ü2"
"PL","Di 1","Eg","Q12","L","M23"
... 和
"PLS","Di 1","Am"," frei "
"PLS","Di 1","Bad"," ----"
"PLS","Di 1","Bk"," frei "
... 其次是几个其他区块（L1 ... L97，M，R1 ... R40，U1 ... U560）。
我知道块的所有可能的“标识符”（AVx，Fx，Gx，.. PL，PLS ..），但也可能省略了一个块，输入文件也没有单行一点都不 输入文件总共包含大约4000行，因此性能不应太低（虽然它不是时间关键的，导入一年可能会完成10次......）。
那么，有没有办法以“智能”和快速的方式完成这项工作，或者我应该逐行读取输入文件，检测并记住第一个值，将当前行添加到结果字符串并循环直到出现新的第一个值？
感谢您的帮助！ 的Heiko