SqlServer常用语句

1、查询每个数据库的连接数

SELECT name,
       COUNT(*) AS CONNECTIONS
FROM
(
    SELECT b.name,
           a.*
    FROM [master].[dbo].[sysprocesses] a
        INNER JOIN [master].[dbo].[sysdatabases] b
            ON a.dbid = b.dbid
) t
GROUP BY t.name
UNION
SELECT '总连接数' AS name,
       COUNT(*) AS CONNECTIONS
FROM master..sysprocesses
UNION
SELECT '允许最大连接数' AS name,
       @@MAX_CONNECTIONS AS CONNECTIONS
ORDER BY CONNECTIONS;

2、查看表名和对应的数据行数

SELECT a.name AS '表名',
       b.rows AS '表数据行数'
FROM sysobjects a
    INNER JOIN sysindexes b
        ON a.id = b.id
WHERE a.type = 'u'
      AND b.indid IN ( 0, 1 )
--and a.name not like 't%'
ORDER BY b.rows DESC;

3、列出每个表所占用空间大小

SELECT t.name AS TableName,
       s.name AS SchemaName,
       p.rows AS RowCounts,
       SUM(a.total_pages) * 8 AS TotalSpaceKB,
       CAST(ROUND(((SUM(a.total_pages) * 8) / 1024.00), 2) AS NUMERIC(36, 2)) AS TotalSpaceMB,
       SUM(a.used_pages) * 8 AS UsedSpaceKB,
       CAST(ROUND(((SUM(a.used_pages) * 8) / 1024.00), 2) AS NUMERIC(36, 2)) AS UsedSpaceMB,
       (SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB,
       CAST(ROUND(((SUM(a.total_pages) - SUM(a.used_pages)) * 8) / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSpaceMB
FROM sys.tables t
    INNER JOIN sys.indexes i
        ON t.object_id = i.object_id
    INNER JOIN sys.partitions p
        ON i.object_id = p.object_id
           AND i.index_id = p.index_id
    INNER JOIN sys.allocation_units a
        ON p.partition_id = a.container_id
    LEFT OUTER JOIN sys.schemas s
        ON t.schema_id = s.schema_id
WHERE t.name NOT LIKE 'dt%'
      AND t.is_ms_shipped = 0
      AND i.object_id > 255
GROUP BY t.name,
         s.name,
         p.rows
ORDER BY UsedSpaceMB desc;