SQL Server 高级SQL

查询view 的列和列数据类型

SELECT COLUMN_NAME, DATA_TYPE 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = 'view name'

树

1. 所有的子树

WITH SubTree AS (
    SELECT tt.ID as SubTreeRoot, tt.ID FROM TreeTable tt
    UNION ALL
    SELECT st.SubTreeRoot, tt.ID
    FROM TreeTable tt
    INNER JOIN SubTree st ON st.ID = tt.ParentID
)
SELECT st.SubTreeRoot, st.ID
FROM SubTree st

2.获取某个子树

WITH SubTree AS (
    SELECT tt.ID as SubTreeRoot, tt.ID 
    FROM TreeTable tt
    WHERE tt.ID= @OneOfIDs
    UNION ALL
    SELECT st.SubTreeRoot, tt.ID
    FROM TreeTable tt
    INNER JOIN SubTree st ON st.ID = tt.ParentID
)
SELECT st.SubTreeRoot, st.ID
FROM SubTree st

3.获取叶子结点

SELECT * 
FROM TreeTable a
WHERE NOT Exists(SELECT 1 FROM TreeTable b WHERE a.ID = b.ParentID)

 查询表的外键

SELECT   
    f.name AS foreign_key_name  
   ,OBJECT_NAME(f.parent_object_id) AS table_name  
   ,COL_NAME(fc.parent_object_id, fc.parent_column_id) AS constraint_column_name  
   ,OBJECT_NAME (f.referenced_object_id) AS referenced_object  
   ,COL_NAME(fc.referenced_object_id, fc.referenced_column_id) AS referenced_column_name  
   ,is_disabled  
   ,delete_referential_action_desc  
   ,update_referential_action_desc  
FROM sys.foreign_keys AS f  
INNER JOIN sys.foreign_key_columns AS fc   
   ON f.object_id = fc.constraint_object_id   
WHERE f.parent_object_id = OBJECT_ID('HumanResources.Employee');  

SELECT 
    r.session_id
    ,st.TEXT AS batch_text
    ,SUBSTRING(st.TEXT, statement_start_offset / 2 + 1, (
            (
                CASE 
                    WHEN r.statement_end_offset = - 1
                        THEN (LEN(CONVERT(NVARCHAR(max), st.TEXT)) * 2)
                    ELSE r.statement_end_offset
                    END
                ) - r.statement_start_offset
            ) / 2 + 1) AS statement_text
    ,qp.query_plan AS 'XML Plan'
    ,r.*
FROM sys.dm_exec_requests r
CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) AS st
CROSS APPLY sys.dm_exec_query_plan(r.plan_handle) AS qp
ORDER BY cpu_time DESC