mysql批量生成修改表和列註釋語句

當咱們在一個數據庫修改完備註後，須要將其致使另外一個服務器上的數據庫中，須要生成批量執行語句，方便操做，注意用change 或modified 進行列的屬性修改時，沒有寫全的話會形成其它屬性的丟失，如

t_users 表中有字段 name 備註名爲 姓名，默認值爲0，若是用alter table t_users change column name name varchar(10) ;那麼備註名就會消失，默認值也會消失。故經過以下語句能夠生成完事的alter 語句

 

生成表修改備註語句

修改數據庫備註名：
單條語句寫法：
alter table t_version comment '版本'

生成批量語句寫法：
select concat("alter table " ,TABLE_NAME, " comment ", "'",TABLE_COMMENT,"'",";") from information_schema.tables 
where information_schema.tables.TABLE_SCHEMA='dwzx' and information_schema.tables.TABLE_TYPE='BASE TABLE'

 

生成列修改

 

單條語句寫法：ALTER TABLE t_content CHANGE name name [type] [character set utf8]  [COLLATE 'utf8_general_ci']  [not null] DEFAULT ['xxx' | null] [auto_increment]  COMMENT  'xxx'
如下有幾種比較典型的寫法(全格式寫)：
ALTER TABLE `t_month_detail` CHANGE `bpu_time` `bpu_time` timestamp NOT NULL  DEFAULT CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP  COMMENT  '發佈時間';--timestamp 類型比較特別，得寫全，以下寫法：
ALTER TABLE `t_month_detail` CHANGE `bpu_time` `bpu_time` timestamp COMMENT  '發佈時間';
默認值不爲null。
ALTER TABLE `t_award_user` CHANGE `id` `id` bigint(20)    NOT NULL   auto_increment  COMMENT  ''; -- 沒有加auto_increment會丟失此屬性
ALTER TABLE `t_agens` CHANGE `intro` `intro` char(10) character set utf8  COLLATE 'utf8_general_ci'  null  DEFAULT null    COMMENT  '機構簡介';
ALTER TABLE `t_news` CHANGE `use` `use` bit(1)    null  DEFAULT b'0'   COMMENT  '是否顯示';



生成批量語句寫法--完整格式寫法(嘔心瀝血之做)
select concat("ALTER TABLE ","`",col.TABLE_NAME,"`"," CHANGE ","`",col.COLUMN_NAME,"`"," ","`",col.COLUMN_NAME,"`"," ",col.COLUMN_TYPE , " ",
if(col.CHARACTER_SET_NAME is null," ",concat(" character set ",col.CHARACTER_SET_NAME," ")),
if(col.COLLATION_NAME is null," ",concat(" COLLATE ","'",col.COLLATION_NAME,"' ")),
if(col.IS_NULLABLE='NO'," NOT NULL "," null "), 
if(col.COLUMN_DEFAULT is null , if(col.EXTRA='auto_increment' or col.IS_NULLABLE='NO'," "," DEFAULT null ") ,concat(" DEFAULT ",if(col.DATA_TYPE='timestamp' or col.DATA_TYPE='bit' ,col.COLUMN_DEFAULT,concat("'",col.COLUMN_DEFAULT,"'")))),
if(col.EXTRA is null ," ",concat(" ",col.EXTRA," "  )),
" COMMENT "," ","'",col.COLUMN_COMMENT,"'",";") change_column_type
from information_schema.COLUMNS col 
join information_schema.tables  tbl  on col.TABLE_SCHEMA=tbl.TABLE_SCHEMA and col.TABLE_NAME=tbl.TABLE_NAME
where col.TABLE_SCHEMA='dwzx' and tbl.TABLE_TYPE='BASE TABLE'  ;