select * from student where name like E'%\'%' ●查看表记录总数 方式一: select relname as TABLE_NAME, reltuples as rowCounts from pg_class where relkind = 'r' and relnamespace = (select oid from pg_namespace where nspname='public') order by rowCounts desc; 方式二: select count(*...
✓ 已被采纳 DECLARE variable_col int := (SELECT oid FROM pg_class WHERE relname='tablename'); SELECT * FROM pg_class WHERE oid=variable_col; 手头没 pg 库,没执行,大概意思理解一下。 P.S. variable_col 是变量名,我瞎起的;int 记得改成你那个 oid 的数据类型。 有用1 回复 Ocean: 你...
select pg_size_pretty(pg_total_relation_size('table_name')) as size; 5、查看表中索引大小 select pg_size_pretty(pg_indexes_size('product')); 6、获取各个表中的数据记录数 select relname as TABLE_NAME, reltuples as rowCounts from pg_class where relkind = 'r' order by rowCounts desc 7...
Sort Key: relpages -> Seq Scanonpg_class (cost=0.00..44.02rows=602width=737) (3rows) 2、按SELECT中的位置排序 postgres=#explainselectrelpages,reltuples,relnamefrompg_classorderby2limit1; QUERY PLAN---Limit(cost=47.03..47.03rows=1width=72) -> Sort (cost=47.03..48.54rows=602width=72) ...
gaussdb=# WITH temp_t(name,isdba) AS (SELECT usename,usesuper FROM pg_user) SELECT * FROM temp_t; --查询tpcds.reason表的所有r_reason_sk记录,且去除重复。 gaussdb=# SELECT DISTINCT(r_reason_sk) FROM tpcds.reason; --LIMIT子句示例:获取表中一条记录。 gaussdb=# SELECT * FROM tpcds.re...
pgxc_class是一个系统表,用于存储表的分布相关信息。...这是数据库分布策略的核心元数据表之一,定义了每个表在集群中的分布方式和相关属性。...用于连接pg_class获取表名(relname)等信息。 pclocatortype,定义了表的分布策略 'H'(HASH):基于分布列的哈希值分布到不同的节点。...节点定位:结合nodeoids字...
因此,执行完REVOKE SELECT ON table t1 FROM user3;之后,虽然user3用户没有了表t1的访问权限(通过系统表pg_class的relacl字段可查看t1表的权限),但是他仍然有public的权限,所以仍能访问该表。 处理方法 撤销public的权限后对user3用户的权限单独管控。但是由于REVOKE回public的权限后可能导致原来能访问该表的用户(...
from (select pg_namespace.nspname as 数据库名, pg_class.relname as 表名, cast(obj_description(pg_class.relfilenode,'pg_class') as varchar) as 表中文描述, '' as 表类型, '' as 表创建时间, pg_attribute.attnum as 字段编号, pg_attribute.attname as 字段名, ...
文章目录 基本的SELECT语句 SELECT... SELECT ...FROM 列的别名去除重复行空值参与运算着重号查询常数(查询同时添加常数字段) 显示表结构过滤数据练习题基本的SELECT语句 SELECT… SELECT 1+1, 2+2;# 直接这样写相当于下面这句...选择特定的...
SELECT c.relname,a.,pg_catalog.pg_get_expr(ad.adbin, ad.adrelid, true) as def_value,dsc.description FROM pg_catalog.pg_attribute a INNER JOIN pg_catalog.pg_class c ON (a.attrelid=c.oid) LEFT OUTER JOIN pg_catalog.pg_attrdef ad ON (a.attrelid=ad.adrelid AND a.attnum = ad....