本篇文章將通過儲存過程來判斷列(字段)是否存在。請看詳情。
判斷字段是否存在：drop procedure if exists schema_change;
delimiter //
create procedure schema_change() begin
declare currentdatabase varchar(100);
select database() into currentdatabase;
if not exists (select * from information_schema.columns where table_schema=currentdatabase and table_name = 'rtc_order' and column_name = 'ifupsend') then
alter table rtc_order
add column `ifupsend` bit not null default 0 comment '是否上傳 是否上傳';
end if;
end//
delimiter ;
call schema_change();
mysql 判斷字段否存在，如果存在就修改字段：drop procedure if exists proc_temppro;
if(@count>0) then
alter table 表名 change column `舊列名` `新列名` varchar(30) comment '字段說明';
end if;
end;
call proc_temppro;
drop procedure if exists proc_temppro;
通過儲存過程判斷字段是否存在，不存在則增加：drop procedure if exists pro_addcolumn;
create procedure pro_addcolumn() begin
if not exists(select 1 from information_schema.columns where table_name='component' and column_name='print_check_status') then
alter table component add print_check_status int(10) default 0;
end if;
if not exists(select 1 from information_schema.columns where table_name='component' and column_name='print_check_time') then
alter table component add print_check_time datetime null;
end if;
if not exists(select 1 from information_schema.columns where table_schema=podcloud and table_name='component' and column_name='print_check_back_reason') then
alter table component add print_check_back_reason varchar(500) default null;
end if;
end;
call pro_addcolumn;
drop procedure pro_addcolumn;
drop procedure if exists pro_addindex;
delimiter;
create procedure pro_addindex() begin if not exists (select * from information_schema.statistics where table_schema=currentdatabase and table_name = 'rtc_phototype' and index_name = 'index_name') then
alter table `rtc_phototype` add index index_name ( `imgtype` );
end if;
end;
delimiter;
call pro_addindex();
drop procedure pro_addindex;
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