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存储过程.md

+# SPL基础
+
+## 概述
+
+- SPL例程由开始语句、语句块、结束语句组成
+- SPL例程根据是否返回值，分为存储过程和函数
+- 语句块由SQL和SPL语句组成。
+
+## 基本语法：
+
+```sql
+-- 存储过程
+create procedure proc_name (param1 data_type1,param2 data_type2..)
+    sql_code;
+end procedure;
+
+-- 函数
+create function func_name (param1 data_type1,...)
+returning data_type1 [as id1],data_type2 [as id2]...
+    sql_code;
+end function;
+```
+
+语法：
+
+- 变量声明
+- 变量赋值
+- 条件
+- 循环
+  - goto
+  - loop
+  - for/foreach
+  - while
+- 异常处理
+
+示例：
+
+```sql
+--变量声明
+-- 变量声明
+create procedure test1()
+define m,n int;
+define global i int default 1;
+define global loginname varchar(20) default 'admin';
+end procedure;
+
+create procedure test2()
+define global i int default 0;
+define global username varchar(20) default '';
+insert into t_user values (i,username);
+let i=i+1;
+let username=concat("syn_",to_char(i));
+
+end procedure;
+
+
+-- 变量赋值
+
+create procedure test3()
+define userid int;
+define sex varchar(20);
+let userid,username=1,"m";
+insert into t_user values (userid,sex);
+
+-- let var=value;
+-- let var1,var2=value1,value2;
+-- let var1,var2...=function(args1,args2....);
+-- let var1,var2...=(select col1,col2...from tb);
+
+
+-- case
+
+-- case expr
+-- when val_1 then
+--     code1;
+-- when val_2 then
+--     code2;
+-- else 
+--     code3;
+-- end case;
+
+create function test_func_1(sexcode int)
+returning varchar(10) as sex
+define sex varchar(10);
+case sexcode
+when 1 then
+    let sex='男';
+when 2 then 
+    let sex='女';
+else
+    let sex='未知';
+end case;
+return sex ;
+end function;
+
+-- 循环
+-- goto
+
+-- << lbl_goto >>
+--     spl_code;
+-- if expr then
+--     goto lbl_goto;
+-- end if;
+
+-- loop
+
+-- loop    
+--     if expr then
+--         exit;
+--     end if;
+-- end loop;
+
+-- for/foreach
+
+-- for i in (start to end ) loop
+--     spl_code；
+-- end loop;
+
+-- for i in (start to end ) 
+--     spl_code
+-- end for;
+
+-- foreach select col1,col2,... into var1,var2...from table
+--     spl_code;
+-- end foreach
+
+
+-- while
+
+-- while expr loop
+--     spl_code;
+-- end loop;
+
+-- while expr
+--     spl_code;
+-- end while;
+
+create procedure test4()
+define i int;
+let i=1;
+while i<10
+    insert into table t_user values (i,concat("u_",to_char(i)))
+    let i = i+1
+end while;
+end procedure;
+
+
+
+
+create table t_class(
+    class_id int,
+    class_name varchar(20)
+);
+create table t_student(
+    sid int,
+    username varchar(100),
+    age int,
+    sex varchar(5),
+    class_id int 
+);
+
+
+```
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