命令：mysql> select database();
mysql中select命令類似於其他程式語言裡的print或者write，你可以用它來顯示乙個字串、數字、數學表示式的結果等等。如何使用mysql中select命令的特殊功能？
1.顯示mysql的版本
mysql> select version();
| version() |
| 6.0.4-alpha-community |
1 row in set (0.02 sec)
2. 顯示當前時間
mysql> select now();
| now() |
| 2009-09-15 22:35:32 |
1 row in set (0.04 sec)
3. 顯示年月日
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. 顯示字串
mysql> select "welecome to my blog!";
| welecome to my blog! |
| welecome to my blog! |
1 row in set (0.00 sec)
5. 當計算器用
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：這裡用到concat()函式，用來把字串串接起來。另外，我們還用到以前學到的as給結果列'concat(f_name, " ", l_name)'起了個假名。
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