mysql運(yùn)行拼接的字符串和導(dǎo)出數(shù)據(jù)

“prepare+execute”

　　學(xué)習(xí)存儲(chǔ)過(guò)程中發(fā)現(xiàn)sql語(yǔ)句有些部分不能夠使用變量，因此采用拼接字符串的形式，然后執(zhí)行字符串代表的SQL?；拘问饺缦拢?br /> ????set @sql=concat('select * from table limit 1');
????PREPARE stmt from @sqlStr;
????EXECUTE stmt;

導(dǎo)出數(shù)據(jù)到文件

　　導(dǎo)出數(shù)據(jù)過(guò)程中需要用到into outfile語(yǔ)句，搭配“prepare+execute”可以方便的批量導(dǎo)出數(shù)據(jù)。示例如下
drop procedure if exists outfile_proc;
delimiter //
create procedure outfile_proc()
begin
declare timex int default 0;
declare tablename varchar(128) default 'table_'
while timex<10 do
????set @sql=concat('select * from table_name limit ',timex,'100 into outfile \'',tabname,timex,'\''); ?
????PREPARE stmt from @sqlStr;
????EXECUTE stmt;
????set timex=timex*100;
end while;
end;
//
delimiter ;
call outfile_proc();
配置導(dǎo)出數(shù)據(jù)到文件所需要的權(quán)限
?
　　如果有權(quán)限，運(yùn)行into outfile語(yǔ)句時(shí)，常會(huì)報(bào)錯(cuò)…