1. 创建索引的语法： CREATE [UNIQUE][CLUSTERED | NONCLUSTERED] INDEX index_name ON {table_name | view_name} [WITH [index_property [,....n]] 说明： UNIQUE: 建立唯一索引。 CLUSTERED: 建立聚集索引。 NONCLUSTERED: 建立非聚集索引。 Index_property: 索引属性。 UNIQUE索引既可以采用聚集索引结构，也可以采用非聚集索引的结构，如果不指明采用的索引结构，则SQL Server系统默认为采用非聚集索引结构。
2. 删除索引语法： DROP INDEX table_name.index_name[,table_name.index_name] 说明：table_name: 索引所在的表名称。 index_name : 要删除的索引名称。 3. 显示索引信息： 使用系统存储过程：sp_helpindex 查看指定表的索引信息。 执行代码如下： Exec sp_helpindex book1;
4. 索引使用次数
declare @dbid int
select @dbid = db_id()
select objectname=object_name(s.object_id), s.object_id, indexname=i.name, i.index_id
, user_seeks, user_scans, user_lookups, user_updates
from sys.dm_db_index_usage_stats s,
sys.indexes i
where database_id = @dbid and objectproperty(s.object_id,'IsUserTable') = 1
and i.object_id = s.object_id
and i.index_id = s.index_id
order by (user_seeks + user_scans + user_lookups + user_updates) asc
5. 将使用较多的索引排在前面
SELECT objects.name ,
databases.name ,
indexes.name ,
user_seeks ,
user_scans ,
user_lookups ,
partition_stats.row_count
FROM sys.dm_db_index_usage_stats stats
LEFT JOIN sys.objects objects ON stats.object_id = objects.object_id
LEFT JOIN sys.databases databases ON databases.database_id = stats.database_id
LEFT JOIN sys.indexes indexes ON indexes.index_id = stats.index_id
AND stats.object_id = indexes.object_id
LEFT JOIN sys.dm_db_partition_stats partition_stats ON stats.object_id = partition_stats.object_id
AND indexes.index_id = partition_stats.index_id
WHERE 1 = 1
--AND databases.database_id = 7
AND objects.name IS NOT NULL
AND indexes.name IS NOT NULL
AND user_scans>0
ORDER BY user_scans DESC ,
stats.object_id ,
indexes.index_id
6. 查看创建的索引提高了多少性能
SELECT
avg_user_impact AS average_improvement_percentage,
avg_total_user_cost AS average_cost_of_query_without_missing_index,
'CREATE INDEX ix_' + [statement] +
ISNULL(equality_columns, '_') +
ISNULL(inequality_columns, '_') + ' ON ' + [statement] +
' (' + ISNULL(equality_columns, ' ') +
ISNULL(inequality_columns, ' ') + ')' +
ISNULL(' INCLUDE (' + included_columns + ')', '')
AS create_missing_index_command
FROM sys.dm_db_missing_index_details a INNER JOIN
sys.dm_db_missing_index_groups b ON a.index_handle = b.index_handle
INNER JOIN sys.dm_db_missing_index_group_stats c ON
b.index_group_handle = c.group_handle
WHERE avg_user_impact > = 40
7. 查询最占用CPU、执行时间最长命令的sql语句
SELECT TOP 100 execution_count,
total_logical_reads /execution_count AS [Avg Logical Reads],
total_elapsed_time /execution_count AS [Avg Elapsed Time],
db_name(st.dbid) as [database name],
object_name(st.dbid) as [object name],
object_name(st.objectid) as [object name 1],
SUBSTRING(st.text, (qs.statement_start_offset / 2) + 1,
((CASE statement_end_offset WHEN - 1 THEN DATALENGTH(st.text) ELSE qs.statement_end_offset END - qs.statement_start_offset)
/ 2) + 1) AS statement_text
FROM sys.dm_exec_query_stats AS qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS st
WHERE execution_count > 100
ORDER BY 1 DESC;
8. 查询 执行时间最长的命令
SELECT TOP 10 COALESCE(DB_NAME(st.dbid),
DB_NAME(CAST(pa.value as int))+'*',
'Resource') AS DBNAME,
SUBSTRING(text,
-- starting value for substring
CASE WHEN statement_start_offset = 0
OR statement_start_offset IS NULL
THEN 1
ELSE statement_start_offset/2 + 1 END,
-- ending value for substring
CASE WHEN statement_end_offset = 0
OR statement_end_offset = -1
OR statement_end_offset IS NULL
THEN LEN(text)
ELSE statement_end_offset/2 END -
CASE WHEN statement_start_offset = 0
OR statement_start_offset IS NULL
THEN 1
ELSE statement_start_offset/2 END + 1
) AS TSQL,
total_logical_reads/execution_count AS AVG_LOGICAL_READS
FROM sys.dm_exec_query_stats
CROSS APPLY sys.dm_exec_sql_text(sql_handle) st
OUTER APPLY sys.dm_exec_plan_attributes(plan_handle) pa
WHERE attribute = 'dbid'
ORDER BY AVG_LOGICAL_READS DESC ;
9. 查询数据库缺失的索引
SELECT TOP 10
[Total Cost] = ROUND(avg_total_user_cost * avg_user_impact * (user_seeks + user_scans),0)
, avg_user_impact
, TableName = statement
, [EqualityUsage] = equality_columns
, [InequalityUsage] = inequality_columns
, [Include Cloumns] = included_columns
FROM sys.dm_db_missing_index_groups g
INNER JOIN sys.dm_db_missing_index_group_stats s
ON s.group_handle = g.index_group_handle
INNER JOIN sys.dm_db_missing_index_details d
ON d.index_handle = g.index_handle
ORDER BY [Total Cost] DESC;
