KCP 模拟题练习 04 - 元命令 \du 和 \dg

【多选题】KSQL 命令列出数据库中的所有角色或用户的元命令是什么？

• \dr
• \du
• \dn
• \dg

解题思路：

通过 ksql 连接 Kingbase 数据库执行命令查看：

-- 查看对应命令的帮助：
Informational
  (options: S = show system objects, + = additional detail)
  \d[S+]                 list tables, views, and sequences
  \d[S+]  NAME           describe table, view, sequence, or index
  \da[S]  [PATTERN]      list aggregates
  \dA[+]  [PATTERN]      list access methods
  \db[+]  [PATTERN]      list tablespaces
  \dc[S+] [PATTERN]      list conversions
  \dC[+]  [PATTERN]      list casts
  \dd[S]  [PATTERN]      show object descriptions not displayed elsewhere
  \dD[S+] [PATTERN]      list domains
  \ddp    [PATTERN]      list default privileges
  \dE[S+] [PATTERN]      list foreign tables
  \det[+] [PATTERN]      list foreign tables
  \des[+] [PATTERN]      list foreign servers
  \deu[+] [PATTERN]      list user mappings
  \dew[+] [PATTERN]      list foreign-data wrappers
  \df[anptw][S+] [PATRN] list [only agg/normal/procedures/trigger/window] functions
  \dF[+]  [PATTERN]      list text search configurations
  \dFd[+] [PATTERN]      list text search dictionaries
  \dFp[+] [PATTERN]      list text search parsers
  \dFt[+] [PATTERN]      list text search templates
  \dg[S+] [PATTERN]      list roles
  \di[S+] [PATTERN]      list indexes
  \dl                    list large objects, same as \lo_list
  \dL[S+] [PATTERN]      list procedural languages
  \dm[S+] [PATTERN]      list materialized views
  \dn[S+] [PATTERN]      list schemas
  \do[S]  [PATTERN]      list operators
  \dO[S+] [PATTERN]      list collations
  \dp     [PATTERN]      list table, view, and sequence access privileges
  \dpkg[S+] [PATTERN]    list packages
  \dP[itn+] [PATTERN]    list [only index/table] partitioned relations [n=nested]
  \drds [PATRN1 [PATRN2]] list per-database role settings
  \dRp[+] [PATTERN]      list replication publications
  \dRs[+] [PATTERN]      list replication subscriptions
  \ds[S+] [PATTERN]      list sequences
  \dt[S+] [PATTERN]      list tables
  \dT[S+] [PATTERN]      list data types
  \du[S+] [PATTERN]      list roles
  \dv[S+] [PATTERN]      list views
  \dx[+]  [PATTERN]      list extensions
  \dy     [PATTERN]      list event triggers
  \l[+]   [PATTERN]      list databases
  \sf[+]  FUNCNAME       show a function's definition
  \sv[+]  VIEWNAME       show a view's definition
  \z      [PATTERN]      same as \dp

-- 测试选项中的命令输出
test=# \du
                                   List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 kcluster  | Cannot login                                               | {}
 sao       | No inheritance                                             | {}
 sso       | No inheritance                                             | {}
 system    | Superuser, Create role, Create DB, Replication, Bypass RLS | {}


test=# \dg
                                   List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 kcluster  | Cannot login                                               | {}
 sao       | No inheritance                                             | {}
 sso       | No inheritance                                             | {}
 system    | Superuser, Create role, Create DB, Replication, Bypass RLS | {}


test=# \dr
invalid command \dr
Try \? for help.
test=# \dn
      List of schemas
       Name       | Owner
------------------+--------
 anon             | system
 dbms_sql         | system
 perf             | system
 public           | system
 src_restrict     | system
 sys_hm           | system
 sysaudit         | system
 sysmac           | system
 wmsys            | system
 xlog_record_read | system
(10 rows)

可以看到 \du 和 \dg 都是查看角色信息的命令，而 \dr 命令不存在，\dn 是查看模式信息。