Question

我有一个使用cvs importer将数据插入mysql的函数有问题的原始代码如下：

{
      $sql = "LOAD DATA INFILE '".@mysql_escape_string($this->file_name).
             "' INTO TABLE `".$this->table_name. 
             "` FIELDS TERMINATED BY '".@mysql_escape_string($this->field_separate_char).
             "' OPTIONALLY ENCLOSED BY '".@mysql_escape_string($this->field_enclose_char).
             "' ESCAPED BY '".@mysql_escape_string($this->field_escape_char).
             "' ".
             ($this->use_csv_header ? " IGNORE 1 LINES " : "")
             ."(`".implode("`,`", $this->arr_csv_columns)."`)";
      $res = mysql_query($sql);
      $this->error = mysql_error();
    }

我的问题是我如何才能做到这一点，如果只有更新记录到该表而不重新插入新记录，因为我想插入多个记录，然后再次上传它们，但首先上传＃LL null然后更新将采用值

Answer 1

看起来像MySQL has support for temporary tables，因此一种解决方案是将CSV数据插入临时表，然后将其加入永久数据以确定要更新的行。

简化示例（假设您的目标表名为datatable，主键为data_id，列field_a和field_b）：

CREATE TEMPORARY TABLE temp_bulk_inserted_datatable LIKE datatable;

LOAD DATA INFILE '/path/to/data.csv' INTO TABLE temp_bulk_inserted_datatable;

-- Update rows that already exist with new data from the file
UPDATE
    datatable as OLD
JOIN
    -- Inner Join, so that only matching rows will be touched
    temp_bulk_inserted_datatable as NEW
    ON OLD.data_id = NEW.data_id
SET
    OLD.field_a = NEW.field_a,
    OLD.field_b = NEW.field_b;

-- Insert new rows from the CSV file which don't yet exist
INSERT INTO datatable
    ( data_id, field_a, field_b )
SELECT
    NEW.data_id, NEW.field_a, NEW.field_b
FROM
    temp_bulk_inserted_datatable as NEW
LEFT JOIN
    -- Left Outer Join: we want to know about non-matches...
    datatable as OLD
    ON OLD.data_id = NEW.data_id
WHERE
    -- ...in fact, we want ONLY the non-matches
    OLD.data_id IS NULL;

DROP TABLE temp_bulk_inserted_datatable;

（请注意，我实际上并没有使用MySQL，所以我的一些语法可能略有偏差，但从我在手册中读到的内容来看，上面应该是正确的。）

我可以将该功能添加为ON DUPLICATE KEY UPDATE

1 个答案: