ROW_NUMBER()函数，它允许您通过某些东西“分区”数据 - 比如这里的 col1- 并获得每个数据分区的增量数字。如果您只想要每个“分区”的第一个条目，只需这样查询（使用公用表表达式 - CTE）：;WITH Distincts AS ( SELECT ID, col1, col2, ROW_NUMBER() OVER (PARTITION BY col1 ORDER BY ID)...
DISTINCT 会将全部数据打到一个 reducer 上执行,造成严重的数据倾斜,耗时巨大。 2.1 ROW_NUMBER() OVER DISTINCT 的两个问题,用 ROW_NUMBER() OVER 可解。比如,如果我们要按 key1 和 key2 两列为 key 去重,就会写出这样的代码: WITH temp_table AS ( SELECT key1, key2, [columns]..., ROW_NUMBER()...
row_number() over (order by T_EQ_BA_EQUIPMENT_ID) Rowid ,t1.这里的Rowid 不用单引号 ,
distinct可以对窗口函数的计算结果进行去重,即distinct可以配合窗口函数使用。命令示例如下: SET odps.sql.allow.fullscan=true; SELECT DISTINCT sale_date, ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY total_price) AS rn FROM sale_detail; 返回结果如下。 +---+---+ | sale_date | rn | +...
select 1; select [distinct] column_name_list from table_name; select * from table_name; select * from employee where name != 'Lucy' limit 5; CTE和嵌套查询 CTE(Common Table Expression) CTE语法: with t1 as (select...) select * from t1 ...
[ALL|DISTINCT|DISTINCTROW] select_expr[, select_expr]... [FROM table_references [WHERE where_condition] [GROUP BY{col_name|expr|position}] [HAVING where_condition] [WINDOW window_name AS(window_spec) [, window_name AS(window_spec)]...] ...
USE AdventureWorks; GO SELECT DISTINCT Title FROM HumanResources.Employee ORDER BY Title; GO D. 使用 SELECT INTO 创建表 以下第一个示例将在 tempdb 中创建一个名为 #Bicycles 的临时表。若要使用该表,则必须使用与下面显示的名称完全相同的名称进行引用。这包括数字符号 (#)。 SQL 复制 USE tempdb; ...
谨慎使用递归语句(WITH RECURSIVE),需明确数据重复度和终止条件,确保递归可按预期结束。 更多开发设计规范参见总体开发设计规范。 语法格式 查询数据 [ WITH [ RECURSIVE ] with_query [, ...] ] SELECT [/*+ plan_hint */] [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] { * | {expressio...
[ WITH <common_table_expression> [ , ...n ] ] SELECT <select_criteria> [ ; ] <select_criteria> ::= [ TOP ( top_expression ) ] [ ALL | DISTINCT ] { * | column_name | expression } [ , ...n ] [ FROM { table_source } [ , ...n ] ] [ WHERE <search_condition> ] [...
realsatan sun wrote: > could this be OK? > > $sql_make = 'SELECT DISTINCT make FROM vehicles'; > > $query_make = mysql_query($sql_make); > $i=0; > while($row = mysql_fetch_row($query_make)) > { > echo $row[0]; ...