laravel chunkById 分块查询 使用时容易出现的问题
1. SQLSTATE[23000]: Integrity constraint violation: 1052 Column ‘id’ in where clause is ambiguous
使用chunkById时，单表进行分块查询，是不会出现id重复的，当用两个表进行 join 查询，如果两个表都存在ID，则会报以上的错误信息
DB::table('table1')->select(['table1.id'])->join('table2', 'table1.id', '=', 'table2.id')->orderBy('table1.id')->chunkById(100, function ($results) {});
如何解决：需要指定第三个参数是用哪个表的ID，例如 table1.id，
需要指定第四个参数，参数形参为 $alias,
$lastId = $results->last()->{$alias};
意为查询出数据以后获取对应的属性，来查询最大值，相当于只要在查询的字段中取值即可, 例如 id
如果不指定第四个参数：会报 Undefined property: stdClass::$table1.id
$alias = $alias ?: $column;
第一页执行完成以后，来查询最大的ID， $alias = table1.id
$results->last()->table1.id
查询出的值内并不会有 table1.id 的key
以下为源码：
/*** Chunk the results of a query by comparing numeric IDs.** @param int $count* @param callable $callback* @param string $column* @param string $alias* @return bool*/public function chunkById($count, callable $callback, $column = 'id', $alias = null){$alias = $alias ?: $column;$lastId = 0;do {$clone = clone $this;// We'll execute the query for the given page and get the results. If there are// no results we can just break and return from here. When there are results// we will call the callback with the current chunk of these results here.$results = $clone->forPageAfterId($count, $lastId, $column)->get();$countResults = $results->count();if ($countResults == 0) {break;}// On each chunk result set, we will pass them to the callback and then let the// developer take care of everything within the callback, which allows us to// keep the memory low for spinning through large result sets for working.if ($callback($results) === false) {return false;}$lastId = $results->last()->{$alias};unset($results);} while ($countResults == $count);return true;}```
