sql server sql.Where("sku.BarCode like @0", "%" + search.BarCode.Trim() + "%");
like CONCAT('%',@{0},'%')
SHOW PROFILE ALL FOR QUERY 12
replace into
INSERT INTO table (a,b,c) VALUES (1,2,3) ON DUPLICATE KEY UPDATE c=c+1;
show slave status;
enforce_gtid_consistency
SELECT UNIX_TIMESTAMP('2009-08-06') ;
SELECT UNIX_TIMESTAMP() ;
SELECT FROM_UNIXTIME(1502184955,'%Y-%m-%d %H:%i:%s');
SELECT FROM_UNIXTIME(substring('1502184608028',1,10),'%Y-%m-%d %H:%i:%s');
select date_format(from_unixtime(substring('1472009536350',1,10)),'%Y-%m-%d')
select * from table where token regexp '^[0-9]+$';
show status like 'innodb_row_lock%';
show processlist;
找到锁进程，kill id ;
UNLOCK TABLES;
SHOW PROCESSLIST
show full processlist;
SHOW PROFILE CPU,BLOCK IO
https://www.2cto.com/database/201703/618261.html
Binlog Dump GTID Master has sent all binlog to slave; waiting for more updates
1、将字段类型设为 TIMESTAMP
2、将默认值设为 CURRENT_TIMESTAMP
Field LIKE CONCAT('%',@0,'%')
like concat('%,',t.userid,',%')";
SELECT GROUP_CONCAT(field) FROM tbl
regexp
SHOW VARIABLES LIKE '%character_set_server%';
SHOW VARIABLES LIKE '%collation_server%';
SHOW VARIABLES LIKE '%character_set_database%';
SHOW VARIABLES LIKE '%character_set_client%';
SHOW VARIABLES LIKE '%character_set_connection%';
SHOW VARIABLES LIKE '%character_set_connection%';
SHOW VARIABLES LIKE '%character_set_results%';
/*查询*/
SHOW GLOBAL STATUS LIKE 'Com_%' ;
SHOW GLOBAL STATUS LIKE 'innodb_%';
SHOW GLOBAL STATUS LIKE 'slow_%';/*开启日志*/
SHOW processlist；
/*执行计划*/
DESC SELECT* FROM userinfo
SELECT COUNT(*) FROM `studentaccount`;
SHOW PROFILES;
SHOW PROFILE FOR QUERY 10;
/*SQL优化器的 优化后的SQL*
filter在Sserver层过滤后剩下多少满足查询的记录数量
*/
EXPLAIN EXTENDED SELECT SUM(amount) FROM customer a,payment b WHERE 1=1 AND a.customer_id=b.customer_id AND email='1111'
SHOW WARNINGS;
/*
*/
SELECT COUNT(*) FROM payment;
SHOW PROFILES;
SHOW PROFILE FOR QUERY 69;/* 语句能够查看到执行过程中线程中的每个状态和消耗的时间 */
/*
索引情况查看
handler_read_key 的值将很高，这个值代表一个行被索引值读的次数，很低的值表名增加索引得到戏能改善不高，。
hannler_read_rnd_next 的值高
*/
SHOW STATUS LIKE 'handler_read%';
/*
查看进程
*/
SHOW PROCESSLIST;
/*
kill命令使用方法 */
KILL pid
/*
简单的优化方法
1、定期分析表和检查表
*/
ANALYZE TABLE payment;
CHECK TABLE payment;
SELECT * FROM information_schema.TABLES WHERE TABLE_SCHEMA= 'adultedu';
/*
禁用和启用索引
*/
ALTER TABLE tbl_Name DISABLE KEYS;
ALTER TABLE tbl_Name ENABLE KEYS;
SHOW VARIABLES LIKE '%sort_buffer_size%'
SHOW GLOBAL STATUS LIKE '%Sort_%';
SHOW VARIABLES LIKE '%buffer_pool_size%';
SHOW GLOBAL STATUS LIKE 'Innodb_buffer_pool_read_requests';
SHOW GLOBAL STATUS LIKE 'Innodb_buffer_pool_reads';
SHOW VARIABLES LIKE '%max_length%';
/*
b. 查看当前会话隔离级别:
*/
SELECT @@tx_isolation;
/*
c.查看系统隔离级别:
*/
SHOW VARIABLES LIKE '%key_cache_block_size%';
SHOW STATUS LIKE 'key_%';
/*
缓存优化
从索引的角度考虑
Key_reads/ Key_read_requests <0.01
Key_reads / Uptime
Key_blocks_used*key_cache_block_size/key_buffer_size
*/
mysql:
JSON_EXTRACT
SELECT
distinct
(
JSON_EXTRACT(
info,
'$.APPLICATION.Identifier'
)
) ApplicationIdentifier,
JSON_EXTRACT(
info,
'$.APPLICATION.Name'
) Name
NOT REGEXP 'server[0-9]+'
NOT REGEXP '^20[0-9]{2,2}-[0-9]{1,2}-[0-9]{1,2}$'
DATE_FORMAT(create_time,'%Y-%m-%d') = '2017-06-16'
binary platform like "A%"
sql server:
LIKE '[0-9][0-9][0-9][0-9]';
like '192.168.[0-9+].%'
方法1:
Sql Server:
Select * Into new_table_name from old_table_name; 这是sql server中的用:
MYSQL:
Create table new_table_name (Select * from old_table_name);
insert into a select * from b
查询表级锁争用情况
获取InnoDB行锁争用情况
原理分析：create table as是ddl语句，insert into select是dml语句，insert into select每一条记录的时候都会产生undo和redo，整个过程相比create table as产生的redo和undo相当多，因此整个过程会慢也是正常的；但是create table as使用的前提是目标表的结构不存在才能使用；
当有大量数据的时候不推荐使用Insert into as，因为该语句的插入的效率很慢；
