LECT * FROM tab_name;
mysql> SELECT * FROM test1;
+------+-------+---------+------------+-----------+
| num1 | num2 | num3 | num4 | num5 |
+------+-------+---------+------------+-----------+
| 127 | 32767 | 8388607 | 2147483647 | 231456789 |
+------+-------+---------+------------+-----------+
1 row in set (0.00 sec)
字符串也可以变成整型，mysql支持数据类型的转换
mysql> INSERT INTO test1VALUES('1','2','3',45,09);
Query OK, 1 row affected (0.05 sec)
mysql> SELECT * FROM test1;
+------+-------+---------+------------+-----------+
| num1 | num2 | num3 | num4 | num5 |
+------+-------+---------+------------+-----------+
| 127 | 32767 | 8388607 | 2147483647 | 231456789 |
| 1 | 2 | 3| 45 | 9 |
+------+-------+---------+------------+-----------+
2 rows in set (0.00 sec)
mysql> SELECT 1+'1';
+-------+
| 1+'1' |
+-------+
| 2 |
+-------+
1 row in set (0.00 sec)
mysql> SELECT 1+'KAIKEBA';
+-------------+
| 1+'KAIKEBA' |
+-------------+
| 1 |
+-------------+
1 row in set, 1 warning (0.00 sec)
mysql> SELECT 1+'3kaikeba';
+--------------+
| 1+'3kaikeba' |
+--------------+
| 4 |
+--------------+
1 row in set, 1 warning (0.00 sec)
（2）浮点数类型与定点类型
为了测试mysql的浮点数和定点数建立数据表test2:
mysql> CREATE TABLE IF NOT EXISTS test2(
-> Num1 FLOAT(6,2),
-> Num2 DOUBLE(6,2),
-> NUM3 DECIMAL(6,2)
-> );
Query OK, 0 rows affected (0.05 sec)
mysql> SHOW TABLES;
+---------------+
| Tables_in_ran |
+---------------+
| test1 |
| test2 |
+---------------+
2 rows in set (0.00 sec)
向数据表test2中插入范围内的数据
mysql> INSERT INTO test2VALUES(9999.99,9999.99,9999.99);
Query OK, 1 row affected (0.03 sec)
mysql> SELECT * FROM test2;
+---------+---------+---------+
| Num1 | Num2 | NUM3 |
+---------+---------+---------+
| 9999.99 | 9999.99 | 9999.99 |
+---------+---------+---------+
1 row in set (0.00 sec)
当插入的数据整数超出了范围时，报错：
mysql> INSERT INTO test2VALUES(19999.99,9999.99,9999.99);
ERROR 1264 (22003): Out of range value forcolumn 'Num1' at row 1
小数位超过范围时，插入成功，但是报警告信息
ysql> INSERT INTO test2VALUES(23.34567,12.2345,67.8902);
Query OK, 1 row affected, 1 warning (0.02sec)
mysql> SELECT * FROM test2;
+---------+---------+---------+
| Num1 | Num2 | NUM3 |
+---------+---------+---------+
| 9999.99 | 9999.99 | 9999.99 |
| 23.35 | 12.23 | 67.89 |
+---------+---------+---------+
2 rows in set (0.00 sec)?
数值是否会四舍五入呢？都进行四舍五入了。定点数超出范围是会产生一条警告，而浮点型不会有警告。
mysql> INSERT INTO test2VALUES(12.5678,23.5678,34.5678);
Query OK, 1 row affected, 1 warning (0.05sec)
mysql> SELECT * FROM test2;
+---------+---------+---------+
| Num1 | Num2 | NUM3 |
+---------+---------+---------+
| 9999.99 | 9999.99 | 9999.99 |
| 23.35 | 12.23 | 67.89 |
| 12.57 | 23.57 | 34.57 |
+---------+---------+---------+
3 rows in set (0.00 sec)
2.2日期时间类型
（1）Time类型3个字节
mysql> CREATE TABLE IF NOT EXISTStesttime(
-> a Time
-> );
Query OK, 0 rows affected (0.08 sec)
插入时间的第一种形式：
mysql> INSERT testtime VALUES('13:14:24');
Query OK, 1 row affected (0.05 sec)
mysql> SELECT * FROM testtime;
+----------+
| a |
+----------+
| 13:14:24 |
+----------+
1 row in set (0.03 sec)
插入数字0也可以：
mysql> INSERT testtime VALUES(0);
Query OK, 1 row affected (0.06 sec)
mysql> SELECT * FROM testtime;
+----------+
| a |
+----------+
| 13:14:24 |
| 00:00:00 |
+----------+
2 rows in set (0.00 sec)
插入时间是不用分隔符：
mysql> INSERT INTO testtimeva lUES('101010');
Query OK, 1 row affected (0.03 sec)
mysql> SELECT * FROM testtime;
+----------+
| a |
+----------+
| 13:1