2 呼叫儲存過程

　　儲存過程必須使用CALL語句呼叫，並且儲存過程和資料庫相關，如果要執行其他資料庫中的儲存過程，需要指定資料庫名稱，例如CALL dbname.procname。儲存函式的呼叫與MySQL中預定義的函式的呼叫方式相同。
　　呼叫儲存過程示例

mysql> DELIMITER //
mysql> CREATE PROCEDURE CountProc(IN sid INT,OUT num INT)
    -> BEGIN
    -> SELECT COUNT(*) INTO num FROM fruits WHERE s_id=sid;
    -> END
 
 //
Query OK, 0 rows affected

mysql> DELIMITER ;
mysql> CALL CountProc(101,@num);
Query OK, 1 row affected

mysql> SELECT @num;
+------+
| @num |
+------+
|    3 |
+------+
1 row in set

3 檢視儲存過程

3.1 SHOW STATUS檢視狀態

SHOW [PROCEDURE|FUNCTION] STATUS [LIKE 'pattern']

例如：

mysql> SHOW
 
 PROCEDURE STATUS LIKE 'C%'\G;
*************************** 1. row ***************************
                  Db: test
                Name: CountProc
                Type: PROCEDURE
             Definer: [email protected]
            Modified: 2016-02-27 11:06:11
             Created: 2016-02-27 11:06:11
       Security_type: DEFINER
             Comment:
character_set_client: utf8
collation_connection: utf8_general_ci
  Database Collation: latin1_swedish_ci
1 row in set
 
 (0.01 sec)

3.2 SHOW CREATE檢視定義

SHOW CREATE {PROCEDURE|FUNCTION} sp_name

示例：

mysql> SHOW CREATE PROCEDURE CountProc \G;
*************************** 1. row ***************************
           Procedure: CountProc
            sql_mode: NO_ENGINE_SUBSTITUTION
    Create Procedure: CREATE DEFINER=`root`@`localhost` PROCEDURE `CountProc`(IN sid INT,OUT num INT)
BEGIN

SELECT COUNT(*) INTO num FROM fruits WHERE s_id=sid;

END
character_set_client: utf8
collation_connection: utf8_general_ci
  Database Collation: latin1_swedish_ci
1 row in set (0.00 sec)

3.3 從表information.schema.Routines檢視資訊

示例：

mysql> SELECT * FROM information_schema.Routines
    -> WHERE ROUTINE_NAME='CountProc'  AND  ROUTINE_TYPE = 'PROCEDURE' \G
*************************** 1. row ***************************
           SPECIFIC_NAME: CountProc
         ROUTINE_CATALOG: def
          ROUTINE_SCHEMA: test
            ROUTINE_NAME: CountProc
            ROUTINE_TYPE: PROCEDURE
               DATA_TYPE:
CHARACTER_MAXIMUM_LENGTH: NULL
  CHARACTER_OCTET_LENGTH: NULL
       NUMERIC_PRECISION: NULL
           NUMERIC_SCALE: NULL
      DATETIME_PRECISION: NULL
      CHARACTER_SET_NAME: NULL
          COLLATION_NAME: NULL
          DTD_IDENTIFIER: NULL
            ROUTINE_BODY: SQL
      ROUTINE_DEFINITION: BEGIN

SELECT COUNT(*) INTO num FROM fruits WHERE s_id=sid;

END
           EXTERNAL_NAME: NULL
       EXTERNAL_LANGUAGE: NULL
         PARAMETER_STYLE: SQL
        IS_DETERMINISTIC: NO
         SQL_DATA_ACCESS: CONTAINS SQL
                SQL_PATH: NULL
           SECURITY_TYPE: DEFINER
                 CREATED: 2016-02-27 11:06:11
            LAST_ALTERED: 2016-02-27 11:06:11
                SQL_MODE: NO_ENGINE_SUBSTITUTION
         ROUTINE_COMMENT:
                 DEFINER: [email protected]
    CHARACTER_SET_CLIENT: utf8
    COLLATION_CONNECTION: utf8_general_ci
      DATABASE_COLLATION: latin1_swedish_ci
1 row in set (0.01 sec)

4 修改儲存過程

　　使用ALTER語句可以修改儲存過程或函式的特性，只能修改特性，如果想修改過程體只能刪除儲存過程再重新建立。

ALTER {PROCEDURE|FUNCTION} sp_name [characteriss]

例如，修改儲存過程CountProc的定義，將讀寫許可權改為MODIFIES SQL DATA，並指定呼叫者可以執行：

mysql> ALTER  PROCEDURE  CountProc  
MODIFIES SQL DATA
SQL SECURITY INVOKER ; 
Query OK, 0 rows affected

mysql> SELECT SPECIFIC_NAME,SQL_DATA_ACCESS,SECURITY_TYPE
    -> FROM information_schema.Routines
    -> WHERE ROUTINE_NAME='CountProc' AND ROUTINE_TYPE='PROCEDURE';
+---------------+-------------------+---------------+
| SPECIFIC_NAME | SQL_DATA_ACCESS   | SECURITY_TYPE |
+---------------+-------------------+---------------+
| CountProc     | MODIFIES SQL DATA | INVOKER       |
+---------------+-------------------+---------------+
1 row in set

5 刪除儲存過程

DROP {PROCEDURE|FUNCTION} [IF EXISTS] sp_name

示例：

mysql> DROP PROCEDURE CountProc;
Query OK, 0 rows affected

6 其他

為什麼需要儲存過程

有人說，不需要把複雜過程封裝成MySQL儲存過程，用程式（C++/JAVA）也能實現複雜邏輯。如果用程式呼叫API執行，其實效率相對較慢，原因在於你的應用程式要通過引擎把MySQL語句交付給MySQL引擎來執行，那就不如直接讓MySQL負責它最精通最能夠完成的工作，所以可以在開發當中可以將某些常用的操作封裝成儲存過程。

儲存過程與自定義函式的區別

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