mysql update join sql语句总结

首先注意的是你用的是mysql还是sqlserver

此处是针对mysql 进行join进行更新的

mysql> select * from goods;
+------+----------+-------+--------+
| id   | name     | price | cat_id |
+------+----------+-------+--------+
|    9 | meizu    |    67 |     33 |
|    1 | pingguo  |    30 |     11 |
|    2 | pear     |    33 |     22 |
|    3 | tao      |    34 |     33 |
|    4 | apple    |    35 |     11 |
|    5 | hetao    |    30 |     22 |
|    6 | huasheng |    33 |     33 |
|    7 | xiaomi   |    55 |     11 |
|    8 | huawei   |    65 |     22 |
+------+----------+-------+--------+

mysql> select * from sales;
+------+------+--------+
| id   | cnt  | cat_id |
+------+------+--------+
|    1 |    1 |     11 |
|    2 |    2 |     22 |
|    3 |    3 |     33 |
+------+------+--------+

 

update sales a join goods b on a.id=b.id set a.cat_id=b.cat_id  ;

假定我们有两张表，一张表为Product表存放产品信息，其中有产品价格列Price；另外一张表是ProductPrice表，我们要将ProductPrice表中的价格字段Price更新为Price表中价格字段的80%。

在MySQL中我们有几种手段可以做到这一点，一种是update table1 t1, table2 ts ...的方式：

<span class="pln" style="font-family: Arial, 宋体;">UPDATE product p</span><span class="pun" style="font-family: Arial, 宋体;">,</span><span class="pln" style="font-family: Arial, 宋体;"> productPrice ppSET pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">price </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">price </span><span class="pun" style="font-family: Arial, 宋体;">*</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="lit" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">0.8</span><span class="pln" style="font-family: Arial, 宋体;">WHERE p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productId </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productIdAND p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">dateCreated </span><span class="pun" style="font-family: Arial, 宋体;"><</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="str" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">'2004-01-01'</span>

另外一种方法是使用inner join然后更新：

<span class="pln" style="font-family: Arial, 宋体;">UPDATE product pINNER JOIN productPrice ppON p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productId </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productIdSET pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">price </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">price </span><span class="pun" style="font-family: Arial, 宋体;">*</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="lit" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">0.8</span><span class="pln" style="font-family: Arial, 宋体;">WHERE p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">dateCreated </span><span class="pun" style="font-family: Arial, 宋体;"><</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="str" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">'2004-01-01'</span>

另外我们也可以使用left outer join来做多表update，比方说如果ProductPrice表中没有产品价格记录的话，将Product表的isDeleted字段置为1，如下sql语句：

<span class="pln" style="font-family: Arial, 宋体;">UPDATE product pLEFT JOIN productPrice ppON p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productId </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productIdSET p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">deleted </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="lit" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">1</span><span class="pln" style="font-family: Arial, 宋体;">WHERE pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productId IS </span><span class="kwd" style="font-family: Arial, 宋体; color: rgb(0, 0, 139);">null</span>

另外，上面的几个例子都是两张表之间做关联，但是只更新一张表中的记录，其实是可以同时更新两张表的，如下sql：

<span class="pln" style="font-family: Arial, 宋体;">UPDATE product pINNER JOIN productPrice ppON p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productId </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">productIdSET pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">price </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> pp</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">price </span><span class="pun" style="font-family: Arial, 宋体;">*</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="lit" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">0.8</span><span class="pun" style="font-family: Arial, 宋体;">,</span><span class="pln" style="font-family: Arial, 宋体;">p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">dateUpdate </span><span class="pun" style="font-family: Arial, 宋体;">=</span><span class="pln" style="font-family: Arial, 宋体;"> CURDATE</span><span class="pun" style="font-family: Arial, 宋体;">()</span><span class="pln" style="font-family: Arial, 宋体;">WHERE p</span><span class="pun" style="font-family: Arial, 宋体;">.</span><span class="pln" style="font-family: Arial, 宋体;">dateCreated </span><span class="pun" style="font-family: Arial, 宋体;"><</span><span class="pln" style="font-family: Arial, 宋体;"> </span><span class="str" style="font-family: Arial, 宋体; color: rgb(128, 0, 0);">'2004-01-01'</span>

两张表做关联，更新了ProductPrice表的price字段

参考 http://blog.csdn.net/yukaizhao/article/details/8280257