SELECT DISTINCT accountid FROM table; COUNT DISTINCT子句 命令简介 COUNT DISTINCT支持计算去重之后的某一个column的个数,对于该列中出现多次的值只会被计算一次,和COUNT的计算类似,如果该列包含NULL值,它将不会计算在内。 语法说明 精确计算的语法示例如下: SELECT c1, COUNT(DISTINCT c2) FROM table GROUP BY...
SELECTDISTINCTcolumn1, column2 ...FROMtable; Here, column1, column2, ...are the table columns tableis table name from where we retrieve the distinct columns Example: SQL SELECT DISTINCT -- select the unique countries from the customers tableSELECTDISTINCTcountryFROMCustomers; Run Code Here, the...
在SQL查询中,COUNT 和DISTINCT 是两个常用的聚合函数,它们可以组合使用来获取唯一值的数量。COUNT(DISTINCT column_name) 用于返回指定列中不同值的数量。 基础概念 COUNT: 是一个聚合函数,用于计算行数。它可以计算表中的总行数或特定条件下的行数。 DISTINCT: 关键字用于返回唯一不同的值。 相关优势 精确计数:...
SELECT DISTINCT agent_code, ord_amount, cust_code, ord_num: This line specifies that you want to retrieve unique combinations of 'agent_code', 'ord_amount', 'cust_code', and 'ord_num'. The DISTINCT keyword ensures that only unique combinations are returned; any duplicate combinations will ...
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() OVER ( PARTITION BY key1, key2 ORDER BY column ASC ...
在这个示例中,我们从两个表(table1和table2)中选择column1和column2列的值,并使用UNION操作符将两个结果集合并起来。如果想要去除重复的记录,可以在第一个SELECT语句中使用DISTINCT关键字: 抱歉,当前编辑器暂不支持代码块标记为txt语言,您可操作将代码块语言设置为txt ...
Cannot update identity column 'ItemID'. Cannot update the view or function "CTE" because it contains aggregates or a DISTINCT clause. Cannot use an aggregate or a subquery in an expression used for the group by list of a GROUP BY clause. Cannot use the ROLLBACK statement within an INSERT...
说明:count(*)会统计值为 NULL 的行,而 count(列名)不会统计此列为 NULL 值的行。 2. 1 基本使用 可以使用GROUP BY子句将表中的数据分成若干组 SELECT column, group_function(column)FROM table[WHERE condition][GROUP BY group_by_expression][ORDER BY column]; ...
SELECT DISTINCT m.PK.num, m.PK.id FROM HMed m GROUP BY m.PK.num, m.PK.id where PK is a primary key entity class. And it works fine, but now I´m trying to do a SELECT COUNT() for that query, which it turns out to be: SELECT COUNT(t.PK.num) ...
Re: count with select distinct? Ben Huntsman July 20, 2012 06:52PM Re: count with select distinct? laptop alias July 21, 2012 03:19AM Re: count with select distinct? Ben Huntsman July 21, 2012 02:39PM Sorry, you can't reply to this topic. It has been closed....