conn = PQconnectdb(conninfo); if (PQstatus(conn) != CONNECTION_OK) { fprintf(stderr, "Connection to database failed: %s", PQerrorMessage(conn)); exit_nicely(conn); } /* 把整数值 "2" 转换成网络字节序 */ binaryIntVal = htonl((uint32_t) 25); /* 为 PQexecParams 设置参数数组 *...
(https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters.../abstract/query_cache.rb ),在同一个请求周期内,如果没有update/delete/insert的操作,会对相同的sql查询进行缓存,如果文章类别都是相同的话,真正去查询数据库只会有...`categories`.* FROM `categories` WHERE...
sys_connect_by_path(col, separtor): returns the connection path from the root node to the current row. Thecolparameter indicates the name of the column displayed in the path, and theseparatorparameter indicates the connector. connect_by_root(col): displays the top-level node of the node.co...
FROM DUAL; SELECT 100 + 'a' #此时将'a'看做0处理 FROM DUAL; SELECT 100 + NULL # null值参与运算,结果为null FROM DUAL; SELECT 100, 100 * 1, 100 * 1.0, 100 / 1.0, 100 / 2, 100 + 2 * 5 / 2,100 / 3, 100 DIV 0 # 分母如果为0,则结果为null FROM DUAL; # 取模运算: % ...
GaussDB(DWS)数据库中的Ruby是什么用户? 在执行SELECT* FROM pg_user语句查看当前系统的用户时,看到Ruby用户且拥有很多权限。 Ruby用户为官方运维使用账户,GaussDB(DWS)数据库创建后,默认生成Ruby账户,不涉及安全风险,请放心使用。 来自:帮助中心 查看更多 → ...
SET character_set_connection = gbk;SET NAMES GBK; -- 相当于完成以上三个设置-- 校对集 校对集用以排序 SHOW CHARACTER SET [LIKE pattern ]/SHOW CHARSET [LIKE pattern ] 查看所有字符集 SHOW COLLATION [LIKE pattern ] 查看所有校对集 CHARSET 字符集编码 设置字符集编码 COLLATE 校对集编码 设置校对集...
$result = $mysqli->query("SELECT * FROM ". $dbprefix ."eventmessages WHERE event_id = '". $eventID ."' ORDER BY dateposted DESC");while($row = $result->fetch_assoc()) { $objMember->select($row['member_id']); $memInfo = $objMember->get_info_filtered();if($memInfo['profil...
$SELECT*FROMpg_stat_activity ; datid │ datname │ pid │ leader_pid │ usesysid │ usename │ application_name │ client_addr │ client_hostname │ client_port │ backend_start │ xact_start │ query_start │ state_change │ wait_event_type │ wait_event │ state │ backend_xid │...
This error started appearing when upgrading to Rails 5.1. Where a small number of queries would fail raising PG::ConnectionBad: PQsocket() can't get socket descriptor: SELECT ... Expected behavior The db connection should be reconnected ...
语句形式为：Insert into Table2(field1,field2,…) select value1,value2,… from Table1 ...