bitsCN.com
drop procedure if exists pro_rep_shadow_rs;
delimiter |
----------------------------------
-- rep_shadow_rs
-- 用来处理信息的增加,更新和删除
-- 每次只更新上次以来没有做过的数据
-- 根据不同的标志位
-- 需要一个输出的参数,
-- 如果返回为0,则调用失败,事务回滚
-- 如果返回为1,调用成功,事务提交
--
-- 测试方法
-- call pro_rep_shadow_rs(@rtn);
-- select @rtn;
----------------------------------
create procedure pro_rep_shadow_rs(out rtn int)
begin
-- 声明变量,所有的声明必须在非声明的语句前面
declare iLast_rep_sync_id int default -1;
declare iMax_rep_sync_id int default -1;
-- 如果出现异常,或自动处理并rollback,但不再通知调用方了
-- 如果希望应用获得异常,需要将下面这一句,以及启动事务和提交事务的语句全部去掉
declare exit handler for sqlexception rollback;
-- 查找上一次的
select eid into iLast_rep_sync_id from rep_de_proc_log where tbl='rep_shadow_rs';
-- 如果不存在,则增加一行
if iLast_rep_sync_id=-1 then
insert into rep_de_proc_log(rid,eid,tbl) values(0,0,'rep_shadow_rs');
set iLast_rep_sync_id = 0;
end if;
-- 下一个数字
set iLast_rep_sync_id=iLast_rep_sync_id+1;
-- 设置默认的返回值为0:失败
set rtn=0;
-- 启动事务
start transaction;
-- 查找最大编号
select max(rep_sync_id) into iMax_rep_sync_id from rep_shadow_rs;
-- 有新数据
if iMax_rep_sync_id>=iLast_rep_sync_id then
-- 调用
call pro_rep_shadow_rs_do(iLast_rep_sync_id,iMax_rep_sync_id);
-- 更新日志
update rep_de_proc_log set rid=iLast_rep_sync_id,eid=iMax_rep_sync_id where tbl='rep_shadow_rs';
end if;
-- 运行没有异常,提交事务
commit;
-- 设置返回值为1
set rtn=1;
end;
delimiter ;
drop procedure if exists pro_rep_shadow_rs_do;
delimiter |
---------------------------------
-- 处理指定编号范围内的数据
-- 需要输入2个参数
-- last_rep_sync_id 是编号的最小值
-- max_rep_sync_id 是编号的最大值
-- 无返回值
---------------------------------
create procedure pro_rep_shadow_rs_do(last_rep_sync_id int, max_rep_sync_id int)
begin
declare iRep_operationtype varchar(1);
declare iRep_status varchar(1);
declare iRep_Sync_id int;
declare iId int;
-- 这个用于处理游标到达最后一行的情况
declare stop int default 0;
-- 声明游标
declare cur cursor for select id,Rep_operationtype,iRep_status,rep_sync_id from rep_shadow_rs where rep_sync_id between last_rep_sync_id and max_rep_sync_id;
-- 声明游标的异常处理,设置一个终止标记
declare CONTINUE HANDLER FOR SQLSTATE '02000' SET stop=1;
-- 打开游标
open cur;
-- 读取一行数据到变量
fetch cur into iId,iRep_operationtype,iRep_status,iRep_Sync_id;
-- 这个就是判断是否游标已经到达了最后
while stop 1 do
-- 各种判断
if iRep_operationtype='I' then
insert into rs0811 (id,fnbm) select id,fnbm from rep_shadow_rs where rep_sync_id=iRep_sync_id;
elseif iRep_operationtype='U' then
begin
if iRep_status='A' then
insert into rs0811 (id,fnbm) select id,fnbm from rep_shadow_rs where rep_sync_id=iRep_sync_id;
elseif iRep_status='B' then
delete from rs0811 where id=iId;
end if;
end;
elseif iRep_operationtype='D' then
delete from rs0811 where id=iId;
end if;
-- 读取下一行的数据
fetch cur into iId,iRep_operationtype,iRep_status,iRep_Sync_id;
end while; -- 循环结束
close cur; -- 关闭游标
end;bitsCN.com

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL is an open source relational database management system suitable for data storage, management, query and security. 1. It supports a variety of operating systems and is widely used in Web applications and other fields. 2. Through the client-server architecture and different storage engines, MySQL processes data efficiently. 3. Basic usage includes creating databases and tables, inserting, querying and updating data. 4. Advanced usage involves complex queries and stored procedures. 5. Common errors can be debugged through the EXPLAIN statement. 6. Performance optimization includes the rational use of indexes and optimized query statements.

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

InnoDB's lock mechanisms include shared locks, exclusive locks, intention locks, record locks, gap locks and next key locks. 1. Shared lock allows transactions to read data without preventing other transactions from reading. 2. Exclusive lock prevents other transactions from reading and modifying data. 3. Intention lock optimizes lock efficiency. 4. Record lock lock index record. 5. Gap lock locks index recording gap. 6. The next key lock is a combination of record lock and gap lock to ensure data consistency.

The main reasons for poor MySQL query performance include not using indexes, wrong execution plan selection by the query optimizer, unreasonable table design, excessive data volume and lock competition. 1. No index causes slow querying, and adding indexes can significantly improve performance. 2. Use the EXPLAIN command to analyze the query plan and find out the optimizer error. 3. Reconstructing the table structure and optimizing JOIN conditions can improve table design problems. 4. When the data volume is large, partitioning and table division strategies are adopted. 5. In a high concurrency environment, optimizing transactions and locking strategies can reduce lock competition.

In database optimization, indexing strategies should be selected according to query requirements: 1. When the query involves multiple columns and the order of conditions is fixed, use composite indexes; 2. When the query involves multiple columns but the order of conditions is not fixed, use multiple single-column indexes. Composite indexes are suitable for optimizing multi-column queries, while single-column indexes are suitable for single-column queries.

To optimize MySQL slow query, slowquerylog and performance_schema need to be used: 1. Enable slowquerylog and set thresholds to record slow query; 2. Use performance_schema to analyze query execution details, find out performance bottlenecks and optimize.

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.


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