MySQL使用存儲過程，光標的使用的簡單示例

存儲過程一直沒仔細學，今天為了完成實驗，老老實實看了書，在網上看了不少東西，想起來簡單，實現起來不容易啊，經過一個多小時的攻堅克難，總算實現了老師的要求，把完美的命令過程貼在下面，用於以后的改進

 

問題描述：

　　現有三張表，教職工，轉換，論文，教職工記錄學院教職工的基本信息，這里要用的是姓名和所屬系別，轉換是教職工中文名和英文名的轉換關系，論文是教職工所發表的論文信息，其中的作者數據可能是中文名也可能是英文名，要實現的是寫一個存儲過程實現以系中心為參數，查找各系中心發表的論文數。

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mysql> use sstest;
Database changed
mysql> desc 教職工;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| 教職工ID   | int(11)      | NO   | PRI | NULL    | auto_increment |
| 工號       | mediumint(9) | YES  |     | NULL    |                |
| 姓名       | varchar(30)  | NO   |     | NULL    |                |
| 性別       | varchar(5)   | NO   |     | NULL    |                |
| 系中心     | varchar(40)  | YES  |     | NULL    |                |
| 職務       | varchar(30)  | YES  |     | NULL    |                |
| 職稱       | varchar(30)  | YES  |     | NULL    |                |
| 退休前職務 | varchar(30)  | NO   |     | NULL    |                |
| 調離前職務 | varchar(50)  | YES  |     | NULL    |                |
| 調離前所屬 | varchar(50)  | YES  |     | NULL    |                |
| 固定電話   | varchar(11)  | YES  |     | NULL    |                |
| 移動電話   | int(11)      | YES  |     | NULL    |                |
| 出生日期   | date         | YES  |     | NULL    |                |
| 電子郵件   | varchar(30)  | YES  |     | NULL    |                |
| 備注       | varchar(50)  | YES  |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
15 rows in set (0.04 sec)

mysql> desc 轉換;
+--------+-------------+------+-----+---------+-------+
| Field  | Type        | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| 英文名 | varchar(30) | YES  |     | NULL    |       |
| 中文名 | varchar(30) | YES  |     | NULL    |       |
+--------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> desc 論文;
+--------+--------------+------+-----+---------+----------------+
| Field  | Type         | Null | Key | Default | Extra          |
+--------+--------------+------+-----+---------+----------------+
| 成果ID | int(11)      | NO   | PRI | NULL    | auto_increment |
| 作者   | varchar(100) | NO   |     | NULL    |                |
| 題名   | varchar(160) | YES  |     | NULL    |                |
| 刊名   | varchar(160) | YES  |     | NULL    |                |
+--------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

mysql> delimiter //
mysql> drop procedure if exists `get_count_of_paper_of_major`;//
Query OK, 0 rows affected (0.04 sec)

mysql> create procedure get_count_of_paper_of_major(in major_name varchar(40), out count_of_papers int)
    -> reads sql data
    -> begin
    -> declare cnt int default 0;
    -> declare tmp int default 0;
    -> declare tmp_name varchar(30) default "";
    -> declare mycursor cursor for select 英文名 from 教職工,轉換 where 教職工.系中心=major_name and 轉換.中文名=教職工.姓名;
    -> DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET tmp_name = NULL;
    ->
    -> open mycursor;
    -> fetch mycursor into tmp_name;
    -> while(tmp_name is not null)
    -> do
    ->  select count(*) from 論文 where 作者=tmp_name into tmp;
    ->  set cnt=cnt+tmp;
    ->  set tmp=0;
    ->  fetch mycursor into tmp_name;
    -> end while;
    -> close mycursor;
    -> set count_of_papers = cnt;
    -> end
    -> //
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql> call get_count_of_paper_of_major('軟件工程系', @count_of_papers);
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select @count_of_papers;
+------------------+
| @count_of_papers |
+------------------+
|               21 |
+------------------+
1 row in set (0.00 sec)

mysql> call get_count_of_paper_of_major('數字媒體技術系', @count_of_papers);
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select @count_of_papers;
+------------------+
| @count_of_papers |
+------------------+
|                0 |
+------------------+
1 row in set (0.00 sec)

mysql> call get_count_of_paper_of_major('信息安全系', @count_of_papers);
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select @count_of_papers;
+------------------+
| @count_of_papers |
+------------------+
|                2 |
+------------------+
1 row in set (0.00 sec)

mysql>

對比以前寫的語句，恩，好像沒有問題

 

不得不說MySQL在存儲過程和觸發器還是和MS SQL Server，DB2，Oracle的差距還很大，很多的功能就MySQL沒有實現，實現了的也相對比較麻煩，嗯，不管怎么樣，希望MySQL越做越好，以開源戰勝商業！加油