随机从数据库取一条记录

(1) ACCESS: 

SELECT TOP n * FROM [tablename] {WHRER condition} ORDER BY RND(field_name) {ASC/DESC}

(2) SQL SERVER: 

SELECT TOP n * FROM [tablename] {WHRER condition} ORDER BY NEWID() {ASC/DESC}

(3) MYSQL: 

SELECT * FROM [tablename] ORDER BY RAND() {ASC/DESC} LIMIT n

(4) ORACLE: 

SELECT * FROM (SELECT * FROM [tablename] ORDER BY DBMS_RANDOM.VALUE) temp WHERE rownum <= n