MySQL 如何在MySQL的每一行中添加一个值？

您可以使用UPDATE命令将一个值添加到MySQL的每一行。

让我们看一下当列是整数时的情况。其语法如下：

UPDATE yourTableName SET yourIntegerColumnName = yourIntegerColumnName+anyValue;
UPDATE yourTableName SET yourIntegerColumnName = anyValue WHERE yourIntegerColumnName IS NULL;

您可以为日期列名添加一个值。其语法如下：

UPDATE yourTableName SET yourDateColumnName = DATEADD(yourDateColumnName,INTERVAL anyIntegerMonth)

要理解上面的语法，让我们创建一个表。创建表的查询如下：

mysql> create table addEachRowValue
    -> (
    -> Id int NOT NULL AUTO_INCREMENT,
    -> Amount int,
    -> ShippingDate date,
    -> PRIMARY KEY(Id)
    -> );
Query OK, 0 rows affected (0.50 sec)

使用插入命令将一些记录插入表中。查询如下：

mysql> insert into addEachRowValue(Amount,ShippingDate) values(100,'2019-02-21');
Query OK, 1 row affected (0.15 sec)
mysql> insert into addEachRowValue(Amount,ShippingDate) values(10,'2013-04-22');
Query OK, 1 row affected (0.19 sec)
mysql> insert into addEachRowValue(Amount,ShippingDate) values(110,'2015-10-25');
Query OK, 1 row affected (0.15 sec)
mysql> insert into addEachRowValue(Amount,ShippingDate) values(150,'2016-03-27');
Query OK, 1 row affected (0.29 sec)
mysql> insert into addEachRowValue(Amount,ShippingDate) values(190,'2018-12-29');
Query OK, 1 row affected (0.20 sec)

使用select语句显示表中的所有记录。查询如下：

mysql> select *from addEachRowValue;

以下是输出：

+----+--------+--------------+
| Id | Amount | ShippingDate |
+----+--------+--------------+
|  1 |    100 | 2019-02-21   |
|  2 |     10 | 2013-04-22   |
|  3 |    110 | 2015-10-25   |
|  4 |    150 | 2016-03-27   |
|  5 |    190 | 2018-12-29   |
+----+--------+--------------+
5 rows in set (0.00 sec)

这是将一个值添加到整数类型Amount列的每一行的查询：

mysql> update addEachRowValue
     -> set Amount=Amount+20;
Query OK, 5 rows affected (0.85 sec)
Rows matched: 5 Changed: 5 Warnings: 0

现在您可以检查表中Amount列的所有更新值。查询如下：

mysql> select Amount from addEachRowValue;

以下是输出：

+--------+
| Amount |
+--------+
|    120 |
|     30 |
|    130 |
|    170 |
|    210 |
+--------+
5 rows in set (0.00 sec)

这是将一个日期列添加一个值的查询：

mysql> update addEachRowValue
     -> set ShippingDate=adddate(ShippingDate,interval 1 month);
Query OK, 5 rows affected (0.31 sec)
Rows matched: 5 Changed: 5 Warnings: 0

现在您可以从表中检查日期列的所有更新值。查询如下：

mysql> select ShippingDate from addEachRowValue;

以下是输出：

+--------------+
| ShippingDate |
+--------------+
| 2019-03-21   |
| 2013-05-22   |
| 2015-11-25   |
| 2016-04-27   |
| 2019-01-29   |
+--------------+
5 rows in set (0.00 sec)

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