OceanBase Oracle 租户支持一些复杂的分析函数，分析函数通常用于计算累积、移动、居中和报告汇总。OceanBase Oracle 租户支持的分析函数如下表所示：

复杂的分析函数语法格式简单描述如下：

analytic_function ( [ arguments ] ) 
OVER 
(
  [
 PARTITION BY { expr [, expr] …  }
 [ 
ORDER [ SIBLINGS ] BY 
    {  expr | position | c_alias } 
    [ ASC | DESC ] 
    [ NULLS FIRST | NULLS LAST ]    
    [,  { expr | position | c_alias } 
        [ ASC | DESC ] 
        [ NULLS FIRST | NULLS LAST ]
    ] …
   [ 
          { ROWS | RANGE } 
{ BETWEEN 
 { UNBOUNDED PRECEDING | CURRENT ROW | value_expr 
{ PRECEDING | FOLLOWING } 
} AND
{ UNBOUNDED FOLLOWING | CURRENT ROW | value_expr                { PRECEDING | FOLLOWING } 
} 
| 
{ UNBOUNDED PRECEDING | CURRENT ROW| value_expr PRECEDING
}
}
]
]　
    )

示例：用分析函数查询

SELECT * FROM (
    SELECT o_w_id, o_d_id, o_ol_cnt, o_entry_d, rank() OVER (PARTITION BY o_w_id order BY o_entry_d) entry_order 
      FROM ordr
     ORDER BY o_w_id , entry_order
) WHERE entry_order <=5;
SELECT * FROM (
    SELECT o_w_id, o_d_id, o_ol_cnt, o_entry_d, dense_rank() OVER (PARTITION BY o_w_id order BY o_entry_d) entry_order 
      FROM ordr
     ORDER BY o_w_id , entry_order
) WHERE entry_order <=5;
SELECT o_w_id, o_d_id, o_ol_cnt, o_entry_d, first_value(o_c_id) OVER (PARTITION BY o_w_id order BY o_entry_d) first_cid 
  FROM ordr
 ORDER BY o_w_id ;