1、如果只是查询数据库的大小的话，直接使用以下语句即可：

EXEC sp_spaceused

2、为了保证查询结果的实时性，推荐使用下面这个语句来确保统计数据是最新的：

EXEC sp_spaceused @updateusage = N'TRUE';

执行完毕后结果是两个表，第一个表中包含了基本的统计信息，第二个表示更加详细的数据占用情况。

3、查询各表的占用大小

SELECT db_name() as DbName,
    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 总共占用空间MB,
    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 > 0
GROUP BY 
    t.Name, s.Name, p.Rows
ORDER BY 
    总共占用空间MB desc;

4、查询各表的大小–使用存储过程

-- =============================================
-- 描  述：更新查询数据库中各表的大小，结果存储到数据表中
-- =============================================
CREATE PROCEDURE [dbo].[sp_UpdateTableSpaceInfo]
AS
BEGIN
    --查询是否存在结果存储表
    IF NOT EXISTS (SELECT * FROM sysobjects where id = OBJECT_ID(N'temp_tableSpaceInfo') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)
    BEGIN
        --不存在则创建
        CREATE TABLE temp_tableSpaceInfo
        (name NVARCHAR(128), 
        rows char(11), 
        reserved VARCHAR(18),
        data VARCHAR(18),
        index_size VARCHAR(18),
        unused VARCHAR(18))
    END
    --清空数据表
    DELETE FROM temp_tableSpaceInfo

    --定义临时变量在遍历时存储表名称
    DECLARE @tablename VARCHAR(255)

    --使用游标读取数据库内所有表表名
    DECLARE table_list_cursor CURSOR FOR 
    SELECT name FROM sysobjects 
    WHERE OBJECTPROPERTY(id, N'IsTable') = 1 AND name NOT LIKE N'#%%' ORDER BY name

    --打开游标
    OPEN table_list_cursor
    --读取第一条数据
    FETCH NEXT FROM table_list_cursor INTO @tablename 

    --遍历查询到的表名
    WHILE @@FETCH_STATUS = 0
    BEGIN
        --检查当前表是否为用户表
        IF EXISTS (SELECT * FROM sysobjects WHERE id = OBJECT_ID(@tablename) AND OBJECTPROPERTY(id, N'IsUserTable') = 1)
        BEGIN
            --当前表则读取其信息插入到表格中
            EXECUTE sp_executesql N'INSERT INTO temp_tableSpaceInfo EXEC sp_spaceused @tbname', N'@tbname varchar(255)', @tbname = @tablename
        END
        --读取下一条数据
        FETCH NEXT FROM table_list_cursor INTO @tablename 
    END

    --释放游标
    CLOSE table_list_cursor
    DEALLOCATE table_list_cursor
END

GO

用的时候，执行一下存储：

EXEC sp_UpdateTableSpaceInfo
SELECT * FROM temp_tableSpaceInfo