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软件需求设计分析报告(Word原件)

干自闭 2024-08-20 阅读 15

文章目录


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MySQL内置函数

1、日期函数


2、字符串函数

  • 把EMP表中的所有名字中有S的替换为’云南’:
mysql> select replace(ename,'S','云南'),ename from EMP;
+-----------------------------+--------+
| replace(ename,'S','云南')   | ename  |
+-----------------------------+--------+
| 云南MITH                    | SMITH  |
| ALLEN                       | ALLEN  |
| WARD                        | WARD   |
| JONE云南                    | JONES  |
| BLAKE                       | BLAKE  |
| CLARK                       | CLARK  |
| 云南COTT                    | SCOTT  |
| KING                        | KING   |
| TURNER                      | TURNER |
| ADAM云南                    | ADAMS  |
| JAME云南                    | JAMES  |
| FORD                        | FORD   |
| MILLER                      | MILLER |
+-----------------------------+--------+
13 rows in set (0.00 sec)

mysql> 
  • 截取EMP表中ename中的第二个到第三个字符:
mysql> select substring(ename,2,2) , ename from EMP;
+----------------------+--------+
| substring(ename,2,2) | ename  |
+----------------------+--------+
| MI                   | SMITH  |
| LL                   | ALLEN  |
| AR                   | WARD   |
| ON                   | JONES  |
| LA                   | BLAKE  |
| LA                   | CLARK  |
| CO                   | SCOTT  |
| IN                   | KING   |
| UR                   | TURNER |
| DA                   | ADAMS  |
| AM                   | JAMES  |
| OR                   | FORD   |
| IL                   | MILLER |
+----------------------+--------+
13 rows in set (0.00 sec)

mysql>
  • 以首字母小写的方式现实所有员工的姓名:
mysql> select concat(lcase(substring(ename,1,1)),substring(ename,2)),ename from
EMP;
+--------------------------------------------------------+--------+
| concat(lcase(substring(ename,1,1)),substring(ename,2)) | ename  |
+--------------------------------------------------------+--------+
| sMITH                                                  | SMITH  |
| aLLEN                                                  | ALLEN  |
| wARD                                                   | WARD   |
| jONES                                                  | JONES  |
| bLAKE                                                  | BLAKE  |
| cLARK                                                  | CLARK  |
| sCOTT                                                  | SCOTT  |
| kING                                                   | KING   |
| tURNER                                                 | TURNER |
| aDAMS                                                  | ADAMS  |
| jAMES                                                  | JAMES  |
| fORD                                                   | FORD   |
| mILLER                                                 | MILLER |
+--------------------------------------------------------+--------+
13 rows in set (0.00 sec)

mysql>

3、数学函数


4、其他函数


OKOK,MySQL内置函数就到这里,如果你对Linux和C++也感兴趣的话,可以看看我的主页哦。下面是我的github主页,里面记录了我的学习代码和leetcode的一些题的题解,有兴趣的可以看看。

Xpccccc的github主页

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