我正在尝试在匿名代码块（class Team {
//empty class used for binding all the team classes
}
class BlueTeam extends Team {
public static List<String> players = new ArrayList<String>();
}
class PlayerData {
Team playerTeam;
public PlayerData(Team tm){
playerTeam = tm;
}
playerTeam.players // I want to access any subclass that is stored into this "myTeam" object and access its players list
}
class createData {
List<PlayerData> data = new ArrayList<PlayerData>();
// this is what I've tried but I get a null exception
Team team = new BlueTeam();
data.add(new PlayerData(team));
}
）中使用EXECUTE根据定义的备份重新创建视图，但是我无法使其正常工作。这大概是我到目前为止所拥有的：
DO $$ ... BEGIN... END$$带有视图定义备份的表是这样制作的
EXECUTE 'CREATE VIEW image AS (' || (SELECT definition FROM tmp_view_backup WHERE viewname = 'image') || ')';
似乎是select导致我在创建字符串时遇到一些问题，因为结果根本不符合我的预期：
CREATE TABLE tmp_view_backup
AS
(select viewname,definition from pg_views
WHERE schemaname = 'public'
);
这是什么？空行？如果我放弃选择，我会得到一个正常的答案（例如字符串长度为postgres=# select char_length('CREATE VIEW image AS (' || (SELECT definition FROM tmp_view_backup WHERE viewname = 'image') || ')') as f ;
f
---
(1 row)
）。
答案 0 :(得分：3)
您可以使用PSQL \gexec参数。
SELECT format('CREATE VIEW image AS %s ', definition)
FROM tmp_view_backup
WHERE viewname = 'image';\gexec
或在DO块中
DO $$
BEGIN
EXECUTE format('CREATE VIEW image AS %s ', definition)
FROM tmp_view_backup
WHERE viewname = 'image';
END $$;