极客教程将varchar转换为MySQL无符号整数
要将varchar转换为无符号整数，请使用CAST（）函数。我们首先创建一个表−
mysql> create table DemoTable868(Amount varchar(100));
Query OK, 0 rows affected (0.51 sec)
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使用insert命令在表中插入一些记录−
mysql> insert into DemoTable868 values('781');
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable868 values('990');
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable868 values('1002');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable868 values('560');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable868 values('890');
Query OK, 1 row affected (0.26 sec)
mysql> insert into DemoTable868 values('9890');
Query OK, 1 row affected (0.06 sec)
mysql> insert into DemoTable868 values('8723');
Query OK, 1 row affected (0.16 sec)
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使用select语句从表中显示所有记录−
mysql> select *from DemoTable868;
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这将产生以下输出−
+--------+
| Amount |
+--------+
| 781 |
| 990 |
| 1002 |
| 560 |
| 890 |
| 9890 |
| 8723 |
+--------+
7 rows in set (0.00 sec)
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以下是将varchar转换为无符号整数的查询−
mysql> select cast(Amount as unsigned) AS Amount from DemoTable868 order by Amount DESC;
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这将产生以下输出−
+--------+
| Amount |
+--------+
| 9890 |
| 8723 |
| 1002 |
| 990 |
| 890 |
| 781 |
| 560 |
+--------+
7 rows in set (0.01 sec)
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