LYBWWP

/*一次查询出总条数*/ SELECT SQL_CALC_FOUND_ROWS * FROM `system_notice`; SELECT FOUND_ROWS() AS pcount

Sql语句优化和索引 1.Innerjoin和左连接，右连接，子查询 A.inner join内连接也叫等值连接是，left/rightjoin是外连接。 SELECT A.id,A.name,B.id,B.name FROM A LEFT JOIN B ON A.id =B.id; SELECT A.id,A.name,B.id,B.name FROM A RIGHT JOIN...