select * from pg_tables"

select pg_size_pretty(pg_relation_size('t_inventory_product')); // 查看空间大小

select A.relname,B.reltuples  from pg_stat_user_tables A,pg_class B where A.relname=B.relname order by B.reltuples  DESC-- 查询用户所建的表及其表中记录数（非精确值，取决于vacuum的频率，但用于分析足够精度了）

时间查询

$where .= " AND TO_CHAR(time,'YYYY-MM-DD')>='" . $findfromdate . "' AND TO_CHAR(time,'YYYY-MM-DD')<='" . $findtodate . "'";