Question

如何通过一个陈述来选择计数和选择列？

Answer 1

使用COUNT（）窗口聚合，您应该能够完成您想要做的事情。但是，针对非常大的表的DISTINCT不太可能具有高性能：

SELECT DISTINCT a, b, c, COUNT(*) OVER (PARTITION BY 1) FROM <tablename>;

另一种选择是，但你要触摸桌子两次：</ p>

SELECT a,b,c, MyCount
FROM <tablename>
CROSS JOIN
    (SELECT COUNT(*) AS MyCount
     FROM <tablename>
    )

Answer 2

如果你只是想看看你的桌子有什么“形状”，这样的东西就可以了。但是，如果您想知道给定查询的列/行计数，可能会有可能，但我不知道该怎么做

; WITH ROW_COUNTS AS
(
SELECT
    s.[Name] as [SchemaName]
,   t.[name] as [TableName]
,   SUM(p.rows) as [RowCounts]
FROM 
    sys.schemas s
    LEFT JOIN 
        sys.tables t
        ON s.schema_id = t.schema_id
    LEFT JOIN 
        sys.partitions p
        ON t.object_id = p.object_id
    LEFT JOIN  
        sys.allocation_units a
        ON p.partition_id = a.container_id
WHERE 
    p.index_id  in(0,1) -- 0 heap table , 1 table with clustered index
    AND p.rows is not null
    AND a.type = 1  -- row-data only , not LOB
GROUP BY 
    s.[Name]
,   t.[name]
)
, COLUMN_COUNTS AS
(
SELECT
    s.[Name] as [SchemaName]
,   t.[name] as [TableName]
,   COUNT(c.column_id) as [ColumnCounts]
FROM 
    sys.schemas s
    INNER JOIN 
        sys.tables t
        ON s.schema_id = t.schema_id
    INNER JOIN
        sys.columns c
        ON C.object_id = T.object_id
GROUP BY 
    s.[Name]
,   t.[name]
)
SELECT
    CC.SchemaName
,   CC.TableName
,   RC.RowCounts
,   CC.ColumnCounts
FROM
    COLUMN_COUNTS CC
    INNER JOIN
        ROW_COUNTS RC
        ON RC.SchemaName = CC.SchemaName
        AND RC.TableName = CC.TableName
ORDER BY
    1,2

针对主人

运行的结果

SchemaName  TableName               RowCounts   ColumnCounts
dbo         Hold_Cluster_Status     0           10
dbo         MSreplication_options   3           6
dbo         spt_fallback_db         0           8
dbo         spt_fallback_dev        0           10
dbo         spt_fallback_usg        0           9
dbo         spt_monitor             1           11
dbo         spt_values              2506        6

Answer 3

我不是100％你想要的，但这是一个可能的例子......

SELECT
  a,
  b,
  c,
  (SELECT COUNT(*) FROM yourTable) as table_count
FROM
  yourTable

使用一个sql查询选择Rowcount和列数？

3 个答案: