MySQL用法

查询数据库表

通过查询INFORMATION_SCHEMA.TABLES查询数据库表的结构信息

SELECT  *  FROM  INFORMATION_SCHEMA.TABLES

WHERE TABLE_NAME =’table_name’ and TABLE_SCHEMA = 'database_name'

-- 查询所有表所有列名

SELECT COLUMN_NAME,TABLE_NAME, TABLE_SCHEMA, COLUMN_COMMENT FROM INFORMATION_SCHEMA.COLUMNS where TABLE_SCHEMA like 'ykee%';

查询结果导出文件

在查询语句后面加上into  outfile 文件路径，可将查询结果导出到文件，文件格式自定

SELECT CONCAT('delete from ',TABLE_NAME,';') FROM INFORMATION_SCHEMA.TABLES

WHERE TABLE_NAME like 'dep_system_doc%'  and TABLE_SCHEMA = 'acm_gaj'

into  outfile  "d://clear_dep_system_doc_.xls";

连表修改

UPDATE trc_track t, cst_customer c
SET t.org_id = c.org_id
WHERE t.org_id is null and t.customer_id = c.id

-- 清除前缀空格
select dic_key from kn_bc_dictionary where dic_key like'% ';
select SUBSTR(dic_key FROM 1 FOR LENGTH(dic_key)-1) from kn_bc_dictionary where dic_key like'% ';
-- 清除后缀空格
select dic_key from kn_bc_dictionary where dic_key like' %';
select SUBSTR(dic_key FROM 2 FOR LENGTH(dic_key)) from kn_bc_dictionary where dic_key like' %';
-- 中间空格改为下划线
select dic_key from kn_bc_dictionary where dic_key like'% %';
select dic_key, REPLACE(dic_key,' ','_') from kn_bc_dictionary where dic_key like'% %';