Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies如何在 MySQL 中更新字段以将值添加到现有值？
可以在 UPDATE 和 SET 命令的帮助下更新字段以将值添加到现有值。语法如下所示 −
UPDATE yourTableName SET yourColumnName = yourColumnName+integerValueToAdd WHERE yourCondition;
为了理解以上语法，让我们创建一个表。创建表的查询如下 −
mysql> create table addingValueToExisting -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(30), -> GameScore int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.58 sec)
使用 insert 命令在表中插入记录。查询如下 −
mysql> insert into addingValueToExisting(Name,GameScore) values('John',89);
Query OK, 1 row affected (0.11 sec)
mysql> insert into addingValueToExisting(Name,GameScore) values('Mike',56);
Query OK, 1 row affected (0.28 sec)
mysql> insert into addingValueToExisting(Name,GameScore) values('Sam',99);
Query OK, 1 row affected (0.18 sec)
mysql> insert into addingValueToExisting(Name,GameScore) values('Carol',100);
Query OK, 1 row affected (0.17 sec)
mysql> insert into addingValueToExisting(Name,GameScore) values('David',67);
Query OK, 1 row affected (0.25 sec)
mysql> insert into addingValueToExisting(Name,GameScore) values('Bob',78);
Query OK, 1 row affected (0.14 sec)使用 select 语句显示表中的所有记录。查询如下 −
mysql> select *from addingValueToExisting;
输出如下 −
+----+-------+-----------+ | Id | Name | GameScore | +----+-------+-----------+ | 1 | John | 89 | | 2 | Mike | 56 | | 3 | Sam | 99 | | 4 | Carol | 100 | | 5 | David | 67 | | 6 | Bob | 78 | +----+-------+-----------+ 6 rows in set (0.00 sec)
更新字段以将值添加到现有值。对于我们的示例，让我们通过添加 10 将 100 更新为 110。查询如下 −
mysql> update addingValueToExisting set GameScore = GameScore+10 where Id = 4; Query OK, 1 row affected (0.23 sec) Rows matched − 1 Changed − 1 Warnings − 0
检查特定记录是否已更新。查询如下 −
mysql> select *from addingValueToExisting where Id = 4;
输出如下 −
+----+-------+-----------+ | Id | Name | GameScore | +----+-------+-----------+ | 4 | Carol | 110 | +----+-------+-----------+ 1 row in set (0.00 sec)
查看以上输出，值 100 增加 10，即为现在的 110。
更新于: 30-Jul-2019
8K+ 阅读
广告