HELP

Purpose

You can use this statement to return the search results in the help table. The search string can contain percent signs (%) and underscores (_).

The search string can match a category or one or more topics.

• Query the list of top-level help categories:

  HELP 'contents';
  

• Query the topics of a help category. For example, search for data types:

  HELP 'data_types';
  

• Use one or more associated keywords to query a specific help topic:

  HELP 'create table'
  

  The query results contain the following information:

  • name: the name of the topic.

  • description: the descriptive help text for the topic.

Syntax

HELP 'search_string';

search_string:
   contents | data_types | theme

Parameters

Examples

• Query the directories of all help information.

  obclient> HELP 'contents';
  You asked for help about help category: "Contents"
  For more information, type 'help <item>', where <item> is one of the following
  categories:
     Data Types
     Functions
     Operator
     Escape character
     Data Definition
     Data Manipulation
     Transaction Statements
     Prepared Statements
     Compound Statements
     Administration
     Utility
  

• Query the numeric data types.

  obclient> HELP 'Numeric Types';
  You asked for help about help category: "Numeric Types"
  For more information, type 'help <item>', where <item> is one of the following
  topics:
     TINYINT
     BOOL,BOOLEAN
     SMALLINT
     MEDIUMINT
     INT
     INTEGER
     BIGINT
     FLOAT
     DOUBLE
     DOUBLE PRECISION
     FLOAT(p)
     DECIMAL
     NUMERIC
  

• Query the method for using the KILL statement.

  obclient> HELP 'KILL';
  Name: 'KILL'
  Description:
  
    Syntax:
  
    KILL [GLOBAL | LOCAL] [CONNECTION | QUERY] 'sessionid'
  
    Each connection to OceanBase Database runs in an independent thread. You can use the SHOW PROCESSLIST statement to query the ongoing threads and use the KILL thread_id statement to terminate a thread.
  
  • KILL CONNECTION terminates the connection with the specified thread ID, like the KILL statement without a modifier.
  
  • KILL QUERY terminates the ongoing statement of the connection but retains the current status of the connection.
  If you have the PROCESS privilege, you can view all threads. If you have the SUPER privilege, you can terminate all threads and statements. Otherwise, you can view and terminate only your own threads and statements.
  

• Query the syntax of the SELECT statement.

  obclient> HELP SELECT
  Name: 'SELECT'
  Description:
  
    You can use this statement to query data from a table.
  
    Basic queries
  
    Syntax:
  
    SELECT
      [ALL | DISTINCT]
        selectexpr [AS othername] [, selectexpr ...]
        [FROM table_references]
          [WHERE where_conditions]
      [GROUP BY group_by_list]
      [HAVING search_conditions]
      [ORDER BY order_list]
      [LIMIT {[offset,] rowcount | rowcount OFFSET offset}]
          [FOR UPDATE];