• create procedure用來創建存儲過程，create function用來創建函數
• 函數與存儲過程最大的區別就是函數調用有返回值，調用存儲過程用call語句，而調用函數就直接引用函數名+參數即可
• Definer和sql security子句指定安全環境
• Definder是MySQL的特殊的訪問控制手段，當數據庫當前沒有這個用戶權限時，執行存儲過程可能會報錯
• sql secuirty的值決定了調用存儲過程的方式，取值 ：definer（默認）或者invoker definer:在執行存儲過程前驗證definer對應的用戶如：cdq@127.0.0.1是否存在，以及是否具有執行存儲過程的權限，若沒有則報錯invoker:在執行存儲過程時判斷inovker即調用該存儲過程的用戶是否有相應權限，若沒有則報錯
• IN,OUT,INOUT三個參數前的關鍵詞只適用於存儲過程，對函數而言所有的參數默認都是輸入參數
• IN輸入參數用於把數值傳入到存儲過程中；OUT輸出參數將數值傳遞到調用者，初始值是NULL；INOUT輸入輸出參數把數據傳入到存儲過程，在存儲過程中修改之后再傳遞到調用者
• Delimiter命令是改變語句的結束符，MySQL默認的結束符為;號，由於procedure和function中的;號並不代表創建的結束，所以要替換成另外的結束符以便表示創建的結束
• Rontine_body子句可以包含一個簡單的SQL語句，也可以包含多個SQL語句，通過begin…end將這多個SQL語句包含在一起
• MySQL存儲過程和函數中也可以包含類似create和drop等DDL語句
• Comment子句用來寫入對存儲過程和函數的注釋
• Language子句用來表示此存儲過程和函數的創建語言
• 存儲過程和函數被標注為deterministic表明當輸入相同的參數是會返回相同的結果，反之如果是not deterministic則表示相同參數不會是相同結果，默認是not deterministic
• 相關屬性短語只有咨詢含義，並不是強制性的約束
• Contains sql表明此存儲過程或函數不包含讀或者寫數據的語句，這是默認屬性
• NO SQL表示此存儲過程或函數不包含SQL語句
• Reads sql data表示此存儲過程包含諸如select的查詢數據的語句，但不包含插入或刪除數據的語句
• Modifies sql data表示此存儲過程包含插入或刪除數據的語句
• Drop procedure/function語句用來刪除指定名稱的存儲過程或函數
• If exists關鍵詞用來避免在刪除一個本身不存在的存儲過程或函數時，MySQL返回錯誤
• Begin…end語句通常出現在存儲過程、函數和觸發器中，其中可以包含一個或多個語句，每個語句用;號隔開
創建存儲過程：
/*在創建之前如果存在同名存儲過程，則刪除*/ drop PROCEDURE if EXISTS create_student; /*修改分分隔符為;;*/ delimiter ;; create PROCEDURE create_student (OUT new_stuid INT,IN new_name VARCHAR(10),IN birth date,IN addr VARCHAR(50),IN gender VARCHAR(10),IN sub_jct VARCHAR(10)) BEGIN /*為new_stuid聲明變量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入數據到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); END;; delimiter ;
調用存儲過程：
mysql> call create_student(@new_stuid,"王超人",'1999-03-04','廣東深圳','男生','計算機'); Query OK, 1 row affected (0.08 sec) mysql> select @new_stuid; +------------+ | @new_stuid | +------------+ | NULL | +------------+ 1 row in set (0.00 sec) mysql> select * from tb_student2; +-------+--------------+--------+------------+--------------+--------+ | stuid | stuname | stusex | stubirth | stuaddr | collid | +-------+--------------+--------+------------+--------------+--------+ | 1001 | 張三 | 0 | 1990-03-04 | ABCabc | 1 | | 1002 | 季墨 | 0 | 1992-02-02 | 湖南長沙 | 1 | | 1033 | 王語嫣 | 1 | 1989-12-03 | 四川成都 | 1 | | 1378 | 紀嫣然 | 1 | 1995-08-12 | 四川綿陽 | 1 | | 1572 | 張子文 | 0 | 1993-07-19 | 陝西咸陽 | 1 | | 1954 | 張學友 | 0 | 1994-09-20 | 福建莆田 | 1 | | 2035 | 東方不敗 | NULL | 1988-06-30 | NULL | 2 | | 3011 | 金大牙 | 0 | 1985-12-12 | 福建莆田 | 3 | | 3755 | 豬腳 | 0 | 1993-01-25 | NULL | 3 | | 3923 | 楊不悔 | 1 | 1985-04-17 | 四川成都 | 3 | | 3924 | 王超人 | 2 | 1999-03-04 | 廣東深圳 | 2 | | 3925 | 王超人2 | 2 | 1999-03-04 | 廣東深圳 | 2 | +-------+--------------+--------+------------+--------------+--------+ 12 rows in set (0.00 sec) mysql>
把上面的例子改造成函數
/*在創建之前如果存在同名函數，則刪除*/ drop FUNCTION if EXISTS create_student_function; /*修改分分隔符為;;*/ delimiter ;; create FUNCTION create_student_function (new_name VARCHAR(10),birth date,addr VARCHAR(50),gender VARCHAR(10),sub_jct VARCHAR(10)) RETURNS INT BEGIN /*為new_stuid聲明變量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入數據到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); RETURN new_stuid; END;; delimiter ;
調用函數
mysql> select create_student("王超人",'1999-03-04','廣東深圳','男生','計算機'); ERROR 1305 (42000): FUNCTION school.create_student does not exist mysql> select create_student_function("王超人",'1999-03-04','廣東深圳','男生','計算機'); +---------------------------------------------------------------------------------------+ | create_student_function("王超人",'1999-03-04','廣東深圳','男生','計算機') | +---------------------------------------------------------------------------------------+ | 3926 | +---------------------------------------------------------------------------------------+ 1 row in set, 8 warnings (0.09 sec) mysql> select create_student_function("王超人",'1999-03-04','廣東深圳','男生','計算機'); +---------------------------------------------------------------------------------------+ | create_student_function("王超人",'1999-03-04','廣東深圳','男生','計算機') | +---------------------------------------------------------------------------------------+ | 3927 | +---------------------------------------------------------------------------------------+ 1 row in set (0.06 sec) mysql> select create_student_function("王超人",'1999-03-04','廣東深圳','男生','計算機'); +---------------------------------------------------------------------------------------+ | create_student_function("王超人",'1999-03-04','廣東深圳','男生','計算機') | +---------------------------------------------------------------------------------------+ | 3928 | +---------------------------------------------------------------------------------------+ 1 row in set (0.05 sec) mysql>
查看所有存儲例程：
mysql> show procedure status like '%create_student%'; +--------+----------------+-----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | Db | Name | Type | Definer | Modified | Created | Security_type | Comment | character_set_client | collation_connection | Database Collation | +--------+----------------+-----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | school | create_student | PROCEDURE | root@% | 2020-08-08 23:08:22 | 2020-08-08 23:08:22 | DEFINER | | utf8 | utf8_general_ci | utf8_bin | +--------+----------------+-----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ 1 row in set (0.00 sec) mysql> show function status like '%create%'; +--------+-------------------------+----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | Db | Name | Type | Definer | Modified | Created | Security_type | Comment | character_set_client | collation_connection | Database Collation | +--------+-------------------------+----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ | school | create_student_function | FUNCTION | root@% | 2020-08-09 16:47:51 | 2020-08-09 16:47:51 | DEFINER | | utf8 | utf8_general_ci | utf8_bin | +--------+-------------------------+----------+---------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+ 1 row in set (0.01 sec) mysql>
查看存儲例程創建語句
mysql> show create procedure create_student; +----------------+-----------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | Procedure | sql_mode | Create Procedure | character_set_client | collation_connection | Database Collation | +----------------+-----------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | create_student | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`@`%` PROCEDURE `create_student`(OUT new_stuid INT,IN new_name VARCHAR(10),IN birth date,IN addr VARCHAR(50),IN gender VARCHAR(10),IN sub_jct VARCHAR(10)) BEGIN /*為new_stuid聲明變量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入數據到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); END | utf8 | utf8_general_ci | utf8_bin | +----------------+-----------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 1 row in set (0.00 sec) mysql> show create function create_student_function; +-------------------------+-----------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | Function | sql_mode | Create Function | character_set_client | collation_connection | Database Collation | +-------------------------+-----------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ | create_student_function | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`@`%` FUNCTION `create_student_function`(new_name VARCHAR(10),birth date,addr VARCHAR(50),gender VARCHAR(10),sub_jct VARCHAR(10)) RETURNS int(11) BEGIN /*為new_stuid聲明變量*/ DECLARE new_stuid int; DECLARE stu_sex int; select max(stuid) into new_stuid from tb_student2; set new_stuid = new_stuid +1; case stu_sex WHEN gender='男生' THEN SET stu_sex=0; WHEN gender='女生' THEN SET stu_sex=1; else set stu_sex=2; END case; /*插入數據到tb_student2*/ insert INTO tb_student2(stuid,stuname,stusex,stubirth,stuaddr,collid) VALUES(new_stuid,new_name,stu_sex,birth,addr,2); RETURN new_stuid; END | utf8 | utf8_general_ci | utf8_bin | +-------------------------+-----------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 1 row in set (0.00 sec) mysql>
存儲例程刪除
mysql> drop function create_student_function; Query OK, 0 rows affected (0.02 sec) mysql> show function status like '%create%'; Empty set (0.00 sec) mysql> drop procedure create_student; Query OK, 0 rows affected (0.03 sec) mysql> show procedure status like '%create_student%'; Empty set (0.00 sec) mysql>
• 標簽label可以加在begin…end語句以及loop, repeat和while語句
• 語句中通過iterate和leave來控制流程，iterate表示返回指定標簽位置，leave表示跳出標簽
使用label標簽
drop PROCEDURE if EXISTS test_procedure; delimiter // CREATE procedure test_procedure(in p1 int,out p2 int) BEGIN label1:LOOP set p1 = p1 + 1; if p1 < 10 then ITERATE label1;END if; LEAVE label1; END LOOP label1; set p2=p1; END; //
調試下：
mysql> call test_procedure(5,@p2); Query OK, 0 rows affected (0.00 sec) mysql> select @p2; +------+ | @p2 | +------+ | 10 | +------+ 1 row in set (0.00 sec) mysql>
Declare語句
• Declare語句通常用來聲明本地變量、游標、條件或者handler
• Declare語句只允許出現在begin … end語句中而且必須出現在第一行
• Declare的順序也有要求，通常是先聲明本地變量，再是游標，然后是條件和handler
存儲過程中的變量
• 本地變量可以通過declare語句進行聲明
• 聲明后的變量可以通過select … into var_list進行賦值，或者通過set語句賦值，或者通過定義游標並使用fetch … into var_list賦值
• 通過declare聲明變量方法
• 使用default指定變量的默認值，如果沒有指定默認值則初始值為NULL
• Type指明該變量的數據類型
• 聲明的變量作用范圍為被聲明的begin … end語句塊之間
• 聲明的變量和被引用的數據表中的字段名要區分開來
變量聲明在上面的例子里用到了，游標后面學到再寫。
查看數據庫中已創建的存儲過程和函數：
