Ask the php Master --- phpnewnew I have two data tables, table a has the titleb field and table titlea has 1000 data records. Table B has 10 data requirements: query the title of Table, if. title in B. title,. store the title to $ array1. if sizeof ($ array1) & gt; ask the php Master --- phpnewnew
I have 2 data tables
Table
Field title
Table B
There is also a field title
Table a has 1000 data records, and Table B has 10 data records.
Requirements:
Query the title of Table a. If a. title is in Table B. title, a. title is saved to $ array1. if sizeof ($ array1)> 5, it is not saved.
If a. title is not in B. title, a. title is saved to $ array2. if sizeof ($ array2)> 5, it is not saved.
My practices
PHP code
$sql="select title from a"........while($tpl2result=mysql_fetch_array($result_sql)) { if(sizeof($array1)<5) { if($this->guolv($tpl2result['title'])) array_push($array1,$tpl2result); } if(sizeof($array2)<5) { if(!$this->guolv($tpl2result['title'])) array_push($array2,$tpl2result); } if(sizeof($newtalk)==5&&sizeof($newvote)==5) { break; exit; } }
Questions:
This method greatly wastes resources, slows down, and learns from Masters ..
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You can google the join operation of SQL statements.
Select * from a left join B on a. title = B. title
Select * from a right join B on a. title = B. title
This eliminates the need for SQL statements to compare the two tables.
In databases, join is highly efficient.
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Yes. You only need a. title table, and left join once is enough. if it is NULL, it is not in Table B.
SQL len
Or php.
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Select title from a left join B on a. title = B. title limit 0, 10
It seems that the limit is 10.
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When I just woke up, the master will stop calling it. you know it, and I know it.
The code has not gone through practice. just as a train of thought, the table must be indexed. However, I have not tested index using the title, and I have little knowledge about Mysql than php.
PHP code
$ Array1 = array (); $ SQL = "SELECT. title As atitle FROM a WHERE. title in (SELECT B. title FROM B) "; $ mysql-> query ($ SQL); $ total = 0; while ($ result = $ mysql-> fetch_assoc ()) {$ array [] = $ result ['atitle']; if ($ total> 5) {break;} $ total ++ ;}$ array2 = array (); $ SQL = "SELECT. title As atitle FROM a WHERE. title not in (SELECT B. title FROM B) "; $ total = 0; while ($ result = $ mysql-> fetch_assoc () {$ array2 [] = $ result ['atitle']; if ($ total> 5) {break;} $ total ++ ;}
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Discussion
Why are you talking about it?
Besides, I still got an error.
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You just need B LEFT JOIN. Dominated by B.
Discussion
Reference:
Select title from a left join B on a. title = B. title limit 0, 10
It seems that the limit is 10.
If none of the first 995 entries are in B, but 996---1000 is in B, it seems that it doesn't work ,,
It seems that there is no proper solution to this kind of requirement. it can only be implemented on the first floor, and the efficiency is higher than that of mine.