Question

我有一个表1，我需要与其他4个表连接。我可以使用子查询编写相同的查询吗？因为如果我使用下面的查询，则需要很长时间（超过40分钟）才能运行。还有其他办法吗？

select T1.ID as IID, T2.Prokey as Pro, T3.pname as IType, T4.pname as Status, T5.pname as Res
from table1 T1
INNER JOIN Table2 T2 on T1.pro = T2.ID
INNER JOIN table3 T3 on T1.itype =T3.ID
INNER JOIN table4 T4 on T1.itatus = T4.ID
INNER JOIN Table5 T5 on T1.Res = T5.ID
group by T2.ID, convert(nvarchar(max), T2.ID), T1.ID, T1.Pkey, T3.pname, T4.pname, T5.pname

Answer 1

这可以为您提供所需索引的基本概念。尝试查看主键的那些。

    SELECT CAST(SERVERPROPERTY('ServerName') AS [nvarchar](256)) AS 

[SQLServer]
    ,db.[database_id] AS [DatabaseID]
    ,db.[name] AS [DatabaseName]
    ,id.[object_id] AS [ObjectID]
    ,id.[statement] AS [FullyQualifiedObjectName]
    ,id.[equality_columns] AS [EqualityColumns]
    ,id.[inequality_columns] AS [InEqualityColumns]
    ,id.[included_columns] AS [IncludedColumns]
    ,gs.[unique_compiles] AS [UniqueCompiles]
    ,gs.[user_seeks] AS [UserSeeks]
    ,gs.[user_scans] AS [UserScans]
    ,gs.[last_user_seek] AS [LastUserSeekTime]
    ,gs.[last_user_scan] AS [LastUserScanTime]
    ,gs.[avg_total_user_cost] AS [AvgTotalUserCost]
    ,gs.[avg_user_impact] AS [AvgUserImpact]
    ,gs.[system_seeks] AS [SystemSeeks]
    ,gs.[system_scans] AS [SystemScans]
    ,gs.[last_system_seek] AS [LastSystemSeekTime]
    ,gs.[last_system_scan] AS [LastSystemScanTime]
    ,gs.[avg_total_system_cost] AS [AvgTotalSystemCost]
    ,gs.[avg_system_impact] AS [AvgSystemImpact]
    ,gs.[user_seeks] * gs.[avg_total_user_cost] * (gs.[avg_user_impact] * 0.01) AS [IndexAdvantage]
    ,'CREATE INDEX [Missing_IXNC_' + OBJECT_NAME(id.[object_id], db.[database_id]) + '_' + REPLACE(REPLACE(REPLACE(ISNULL(id.[equality_columns], ''), ', ', '_'), '[', ''), ']', '') + CASE
        WHEN id.[equality_columns] IS NOT NULL
            AND id.[inequality_columns] IS NOT NULL
            THEN '_'
        ELSE ''
        END + REPLACE(REPLACE(REPLACE(ISNULL(id.[inequality_columns], ''), ', ', '_'), '[', ''), ']', '') + '_' + LEFT(CAST(NEWID() AS [nvarchar](64)), 5) + ']' + ' ON ' + id.[statement] + ' (' + ISNULL(id.[equality_columns], '') + CASE
        WHEN id.[equality_columns] IS NOT NULL
            AND id.[inequality_columns] IS NOT NULL
            THEN ','
        ELSE ''
        END + ISNULL(id.[inequality_columns], '') + ')' + ISNULL(' INCLUDE (' + id.[included_columns] + ')', '') AS [ProposedIndex]
    ,CAST(CURRENT_TIMESTAMP AS [smalldatetime]) AS [CollectionDate]
FROM [sys].[dm_db_missing_index_group_stats] gs WITH (NOLOCK)
INNER JOIN [sys].[dm_db_missing_index_groups] ig WITH (NOLOCK)
    ON gs.[group_handle] = ig.[index_group_handle]
INNER JOIN [sys].[dm_db_missing_index_details] id WITH (NOLOCK)
    ON ig.[index_handle] = id.[index_handle]
INNER JOIN [sys].[databases] db WITH (NOLOCK)
    ON db.[database_id] = id.[database_id]
WHERE id.[database_id] > 4 -- Remove this to see for entire instance

ORDER BY [IndexAdvantage] DESC
OPTION (RECOMPILE);

Answer 2

首先，在table1中创建4个索引：

IX_Table1_pro , IX_Table1_itype , IX_Table1_itatus , IX_Table1_Res 使用此脚本（XXX是列名）

CREATE NONCLUSTERED INDEX IX_Table1_XXX  ON Table1 (XXX)

然后使用列ID

在其他表中创建索引

Answer 3

这是SQL语句：

-- CREATE TABLE 1 INDEXES 

CREATE NONCLUSTERED INDEX IX_Table1_pro
ON Table1 (pro) 

CREATE NONCLUSTERED INDEX IX_Table1_itype 
ON Table1 (itype) 

CREATE NONCLUSTERED INDEX IX_Table1_itatus
ON Table1 (itatus) 

CREATE NONCLUSTERED INDEX IX_Table1_Res
ON Table1 (Res) 

-- CREATE TABLE 2 INDEXES 

CREATE NONCLUSTERED INDEX IX_Table2_ID
ON Table2 (ID) 

-- CREATE TABLE 3 INDEXES 

CREATE NONCLUSTERED INDEX IX_Table3_ID
ON Table3 (ID) 

-- CREATE TABLE 4 INDEXES 

CREATE NONCLUSTERED INDEX IX_Table4_ID
ON Table4 (ID) 

-- CREATE TABLE 5 INDEXES 

CREATE NONCLUSTERED INDEX IX_Table5_ID
ON Table5 (ID)

用一个表加入4个不同的表

3 个答案: