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MySQL中SELECT命令大家都经常在用，下面为您介绍的是MySQL中SELECT命令的几种特殊用法，供您参考学习之用。
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MySQL中SELECT命令类似于其他编程语言里的print或者write，你可以用它来显示一个字符串、数字、数学表达式的结果等等。如何使用MySQL中SELECT命令的特殊功能？
1.显示MYSQL的版本
- mysql> select version();
- +-----------------------+
- | version() |
- +-----------------------+
- | 6.0.4-alpha-community |
- +-----------------------+
- 1 row in set (0.02 sec)
2. 显示当前时间
- mysql> select now();
- +---------------------+
- | now() |
- +---------------------+
- | 2009-09-15 22:35:32 |
- +---------------------+
- 1 row in set (0.04 sec)
3. 显示年月日
- SELECT DAYOFMONTH(CURRENT_DATE);
- +--------------------------+
- | DAYOFMONTH(CURRENT_DATE) |
- +--------------------------+
- | 15 |
- +--------------------------+
- 1 row in set (0.01 sec)
- SELECT MONTH(CURRENT_DATE);
- +---------------------+
- | MONTH(CURRENT_DATE) |
- +---------------------+
- | 9 |
- +---------------------+
- 1 row in set (0.00 sec)
- SELECT YEAR(CURRENT_DATE);
- +--------------------+
- | YEAR(CURRENT_DATE) |
- +--------------------+
- | 2009 |
- +--------------------+
- 1 row in set (0.00 sec)
4. 显示字符串
- mysql> SELECT "welecome to my blog!";
- +----------------------+
- | welecome to my blog! |
- +----------------------+
- | welecome to my blog! |
- +----------------------+
- 1 row in set (0.00 sec)
5. 当计算器用
- select ((4 * 4) / 10 ) + 25;
- +----------------------+
- | ((4 * 4) / 10 ) + 25 |
- +----------------------+
- | 26.60 |
- +----------------------+
- 1 row in set (0.00 sec)
6. 串接字符串
- select CONCAT(f_name, " ", l_name)
- AS Name
- from employee_data
- where title = 'Marketing Executive';
- +---------------+
- | Name |
- +---------------+
- | Monica Sehgal |
- | Hal Simlai |
- | Joseph Irvine |
- +---------------+
- 3 rows in set (0.00 sec)
注意：这里用到CONCAT()函数，用来把字符串串接起来。另外，我们还用到以前学到的AS给结果列'CONCAT(f_name, " ", l_name)'起了个假名。
