Mysql数值数据类型实战-蒲公英云

Mysql数值数据类型实战

一整数数据类型

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二浮点型数据类型

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三创建表tmp1，其中字段x、y、z、m、n数据类型依次为TINYINT、SMALLINT、MEDIUMINT、INT、BIGINT

mysql> CREATE TABLE tmp1 ( x TINYINT,  y SMALLINT,  z MEDIUMINT,  m INT,  n BIGINT );
Query OK, 0 rows affected (0.19 sec)

执行成功之后，便用DESC查看表结构，结果如下：

mysql> DESC tmp1;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| x     | tinyint(4)   | YES  |     | NULL    |       |
| y     | smallint(6)  | YES  |     | NULL    |       |
| z     | mediumint(9) | YES  |     | NULL    |       |
| m     | int(11)      | YES  |     | NULL    |       |
| n     | bigint(20)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
5 rows in set (0.01 sec)

四创建表tmp2，其中字段x、y、z数据类型依次为FLOAT(5,1)、DOUBLE(5,1)和DECIMAL(5,1)，向表中插入数据5.12、5.15和5.123

mysql> CREATE TABLE tmp2 ( x FLOAT(5,1),  y DOUBLE(5,1),  z DECIMAL(5,1) );
Query OK, 0 rows affected (0.30 sec)

向表中插入数据：

mysql> INSERT INTO tmp2 VALUES(5.12, 5.15, 5.123);
Query OK, 1 row affected, 1 warning (0.04 sec)

可以看到在插入数据时，MySQL给出了一个警告信息，使用SHOW WARNINGS;语句查看警告信息：

mysql> SHOW WARNINGS;
+-------+------+----------------------------------------+
| Level | Code | Message                                |
+-------+------+----------------------------------------+
| Note  | 1265 | Data truncated for column 'z' at row 1 |
+-------+------+----------------------------------------+
1 row in set (0.00 sec)