mysql rownum写法_mysql类似oracle rownum写法实例详解

mysql类似oracle rownum写法实例详解

rownum是oracle才有的写法，rownum在oracle中可以用于取第一条数据，或者批量写数据时限定批量写的数量等

mysql取第一条数据写法

SELECT * FROM t order by id LIMIT 1;

oracle取第一条数据写法

SELECT * FROM t where rownum =1 order by id;

ok，上面是mysql和oracle取第一条数据的写法对比，不过这只是rownum的一种用法，rownum还可以用于批量写数据

往t表批量写一万条数据：

insert into t(id,date) select sys_guid(),sysdate from dual connect by rownum<=10000;

oracle原版写法：

select * from (select id,name from t) where rownum to_number(num);

mysql改写后的SQL：

SELECT

*

FROM

(SELECT

tb.*,

@rownum := @rownum + 1 AS rownum

FROM

(SELECT

id,

NAME

FROM

t) tb,

(SELECT

@rownum := 0) r) AS t

WHERE rownum <= CAST(num AS SIGNED INTEGER) ;

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