《MYSQL數據庫mysql批量更新多條記錄的同一個字段為不同值的方法》要點：
本文介紹了MYSQL數據庫mysql批量更新多條記錄的同一個字段為不同值的方法，希望對您有用。如果有疑問，可以聯系我們。
首先mysql更新數據的某個字段,一般這樣寫：MYSQL數據庫
UPDATE mytable SET myfield = 'value' WHERE other_field = 'other_value';
也可以這樣用in指定要更新的記錄：MYSQL數據庫
UPDATE mytable SET myfield = 'value' WHERE other_field in ('other_values');
這里注意 ‘other_values' 是一個逗號(,)分隔的字符串,如：1,2,3MYSQL數據庫
如果更新多條數據而且每條記錄要更新的值不同,可能很多人會這樣寫：MYSQL數據庫
foreach ($values as $id => $myvalue) {
$sql = "UPDATE mytable SET myfield = $myvalue WHERE id = $id";
mysql_query($sql);
}
即是循環一條一條的更新記錄.一條記錄update一次,這樣性能很差,也很容易造成阻塞.MYSQL數據庫
那么能不能一條sql語句實現批量更新呢?MYSQL數據庫
mysql并沒有提供直接的方法來實現批量更新,但是可以用點小技巧來實現.MYSQL數據庫
UPDATE mytable
SET myfield = CASE id
WHEN 1 THEN 'myvalue1'
WHEN 2 THEN 'myvalue2'
WHEN 3 THEN 'myvalue3'
END
WHERE other_field ('other_values')
如果where條件查詢出記錄的id不在CASE范圍內,myfield將被設置為空.MYSQL數據庫
如果更新多個值的話,只需要稍加修改：MYSQL數據庫
UPDATE mytable SET myfield1 = CASE id WHEN 1 THEN 'myvalue11' WHEN 2 THEN 'myvalue12' WHEN 3 THEN 'myvalue13' END, myfield2 = CASE id WHEN 1 THEN 'myvalue21' WHEN 2 THEN 'myvalue22' WHEN 3 THEN 'myvalue23' END WHERE id IN (1,2,3)
這里以php為例,構造這兩條mysql語句：MYSQL數據庫
1、更新多條單個字段為不同值, mysql模式
MYSQL數據庫
$ids_values = array(
1 => 11,
2 => 22,
3 => 33,
4 => 44,
5 => 55,
6 => 66,
7 => 77,
8 => 88,
);
$ids = implode(',', array_keys($ids_values ));
$sql = "UPDATE mytable SET myfield = CASE id ";
foreach ($ids_values as $id=> $myvalue) {
$sql .= sprintf("WHEN %d THEN %d ", $id, $myvalue);
}
$sql .= "END WHERE id IN ($ids)";
echo $sql.";<br/>";
輸出：MYSQL數據庫
UPDATE mytable SET myfield = CASE id WHEN 1 THEN 11 WHEN 2 THEN 22 WHEN 3 THEN 33 WHEN 4 THEN 44 WHEN 5 THEN 55 WHEN 6 THEN 66 WHEN 7 THEN 77 WHEN 8 THEN 88 END WHERE id IN (1,2,3,4,5,6,7,8);
2、更新多個字段為不同值, PDO模式
MYSQL數據庫
$data = array(array('id' => 1, 'myfield1val' => 11, 'myfield2val' => 111), array('id' => 2, 'myfield1val' => 22, 'myfield2val' => 222));
$where_in_ids = implode(',', array_map(function($v) {return ":id_" . $v['id'];}, $data));
$update_sql = 'UPDATE mytable SET';
$params = array();
$update_sql .= ' myfield1 = CASE id';
foreach($data as $key => $item) {
$update_sql .= " WHEN :id_" . $key . " THEN :myfield1val_" . $key . " ";
$params[":id_" . $key] = $item['id'];
$params[":myfield1val_" . $key] = $item['myfield1val'];
}
$update_sql .= " END";
$update_sql .= ',myfield2 = CASE id';
foreach($data as $key => $item) {
$update_sql .= " WHEN :id_" . $key . " THEN :myfield2val_" . $key . " ";
$params[":id_" . $key] = $item['id'];
$params[":myfield1va2_" . $key] = $item['myfield2val'];
}
$update_sql .= " END";
$update_sql .= " WHERE id IN (" . $where_in_ids . ")";
echo $update_sql.";<br/>";
var_dump($params);
輸出：MYSQL數據庫
UPDATE mytable SET myfield1 = CASE id WHEN :id_0 THEN :myfield1val_0 WHEN :id_1 THEN :myfield1val_1 END,myfield2 = CASE id WHEN :id_0 THEN :myfield2val_0 WHEN :id_1 THEN :myfield2val_1 END WHERE id IN (:id_1,:id_2); array (size=6) ':id_0' => int 1 ':myfield1val_0' => int 11 ':id_1' => int 2 ':myfield1val_1' => int 22 ':myfield1va2_0' => int 111 ':myfield1va2_1' => int 222
另外三種批量更新方式MYSQL數據庫
1. replace into 批量更新MYSQL數據庫
replace into mytable(id, myfield) values (1,'value1'),(2,'value2'),(3,'value3');
2. insert into ...on duplicate key update批量更新MYSQL數據庫
insert into mytable(id, myfield1, myfield2) values (1,'value11','value21'),(2,'value12','value22'),(3,'value13','value23') on duplicate key update myfield1=values(myfield2),values(myfield2)+values(id);
3. 臨時表MYSQL數據庫
DROP TABLE IF EXISTS `tmptable`; create temporary table tmptable(id int(4) primary key,myfield varchar(50)); insert into tmptable values (1,'value1'),(2,'value2'),(3,'value3'); update mytable, tmptable set mytable.myfield = tmptable.myfield where mytable.id = tmptable.id;
總結MYSQL數據庫
以上就是這篇文章的全部內容了,希望本文的內容對大家的學習或者工作能帶來一定的幫助,如果有疑問大家可以留言交流.MYSQL數據庫
