sql語(yǔ)句有幾種寫(xiě)法
1：SELECT * FROM tablename ORDER BY RAND() LIMIT 想要獲取的數(shù)據(jù)條數(shù)；

2：SELECT *FROM table WHERE id >= (SELECT FLOOR( MAX(id) * RAND()) FROM table ) ORDER BY id LIMIT 想要獲取的數(shù)據(jù)條數(shù);

3：SELECT * FROM table AS t1 JOIN (SELECT ROUND(RAND() * (SELECT MAX(id) FROM table)) AS id) AS t2 WHERE t1.id >= t2.id ORDER BY t1.id ASC LIMIT 想要獲取的數(shù)據(jù)條數(shù);

4：SELECT * FROM tableWHERE id >= (SELECT floor(RAND() * (SELECT MAX(id) FROM table))) ORDER BY id LIMIT 想要獲取的數(shù)據(jù)條數(shù);

5：SELECT * FROM table WHERE id >= (SELECT floor( RAND() * ((SELECT MAX(id) FROM table)-(SELECT MIN(id) FROM table)) + (SELECT MIN(id) FROM table))) ORDER BY id LIMIT 想要獲取的數(shù)據(jù)條數(shù);

6：SELECT * FROM table AS t1 JOIN (SELECT ROUND(RAND() * ((SELECT MAX(id) FROM table)-(SELECT MIN(id) FROM table))+(SELECT MIN(id) FROM table)) AS id) AS t2 WHERE t1.id >= t2.id ORDER BY t1.id LIMIT 想要獲取的數(shù)據(jù)條數(shù);

1的查詢(xún)時(shí)間>>2的查詢(xún)時(shí)間>>5的查詢(xún)時(shí)間>6的查詢(xún)時(shí)間>4的查詢(xún)時(shí)間>3的查詢(xún)時(shí)間，也就是3的效率最高。