--- Find tables rows count in a database--------------------------------

 Using sys.partitions table :

SELECT
      QUOTENAME(SCHEMA_NAME(sOBJ.schema_id)) + '.' + QUOTENAME(sOBJ.name) AS [TableName]
      , SUM(sPTN.Rows) AS [RowCount]
FROM
      sys.objects AS sOBJ
      INNER JOIN sys.partitions AS sPTN
            ON sOBJ.object_id = sPTN.object_id
WHERE
      sOBJ.type = 'U'
      AND sOBJ.is_ms_shipped = 0x0
      AND index_id < 2 -- 0:Heap, 1:Clustered
GROUP BY
      sOBJ.schema_id
      , sOBJ.name
ORDER BY [TableName]
GO
 Using sys.dm_db_partition_stats table :

SELECT
      QUOTENAME(SCHEMA_NAME(sOBJ.schema_id)) + '.' + QUOTENAME(sOBJ.name) AS [TableName]
      , SUM(sdmvPTNS.row_count) AS [RowCount]
FROM
      sys.objects AS sOBJ
      INNER JOIN sys.dm_db_partition_stats AS sdmvPTNS
            ON sOBJ.object_id = sdmvPTNS.object_id
WHERE
    sOBJ.type = 'U'
      --AND sOBJ.is_ms_shipped = 0x0
      AND sdmvPTNS.index_id < 2
GROUP BY
      sOBJ.schema_id
      , sOBJ.name
ORDER BY [TableName]
GO

Using Count(*) and sp_MSforeachtable proc table (will be slow for large tables):

DECLARE @TableRowCounts TABLE ([TableName] VARCHAR(128), [RowCount] INT) ;
INSERT INTO @TableRowCounts ([TableName], [RowCount])
EXEC sp_MSforeachtable 'SELECT ''?'' [TableName], COUNT(*) [RowCount] FROM ?' ;
SELECT [TableName], [RowCount]
FROM @TableRowCounts
ORDER BY [TableName]
GO

DECLARE @QueryString NVARCHAR(MAX) ;
SELECT @QueryString = COALESCE(@QueryString + ' UNION ALL ','')
                      + 'SELECT '
                      + '''' + QUOTENAME(SCHEMA_NAME(sOBJ.schema_id))
                      + '.' + QUOTENAME(sOBJ.name) + '''' + ' AS [TableName]
                      , COUNT(*) AS [RowCount] FROM '
                      + QUOTENAME(SCHEMA_NAME(sOBJ.schema_id))
                      + '.' + QUOTENAME(sOBJ.name) + ' WITH (NOLOCK) '
FROM sys.objects AS sOBJ
WHERE
      sOBJ.type = 'U'
      AND sOBJ.is_ms_shipped = 0x0
ORDER BY SCHEMA_NAME(sOBJ.schema_id), sOBJ.name ;
EXEC sp_executesql @QueryString
GO

Using  Sys.tables and sys.Indexes:

SELECT '[' + SCHEMA_NAME(t.schema_id) + '].[' + t.name + ']' AS fulltable_name, SCHEMA_NAME(t.schema_id) AS schema_name, t.name AS table_name,
i.rows
FROM sys.tables AS t INNER JOIN
sys.sysindexes AS i ON t.object_id = i.id AND i.indid < 2