50 Useful SQL Queries

In this article I will explain some general purpose queries. I think each developer should have knowledge of these queries. These queries are not related to any specific topic of SQL. But knowledge of such queries can solve some complex tasks and may be used in many scenarios, so I decided to write an article on these queries.
Query 1: Retrieve List of All Database
  1. EXEC sp_helpdb  
Example:
Example
Query 2: Display Text of Stored Procedure, Trigger, View
  1. exec sp_helptext @objname = 'Object_Name'  
Example:
Example
Query 3: Get All Stored Procedure Relate To Database
  1. SELECT DISTINCT o.name, o.xtype  
  2.   
  3. FROM syscomments c  
  4.   
  5. INNER JOIN sysobjects o ON c.id=o.id  
  6.   
  7. WHERE o.xtype='P'  
Example:
Example
To retrieve the View use “V” instead of “P” and for functions use “FN.
Query 4: Get All Stored Procedure Relate To Table
  1. SELECT DISTINCT o.name, o.xtype  
  2.   
  3. FROM syscomments c  
  4.   
  5. INNER JOIN sysobjects o ON c.id=o.id  
  6.   
  7. WHERE c.TEXT LIKE '%Table_Name%' AND o.xtype='P'  
Example:
Example
To retrieve the View use “V” instead of “P” and for functions use “FN.
Query 5: Rebuild All Index of Database
  1. EXEC sp_MSforeachtable @command1="print '?' DBCC DBREINDEX ('?', ' ', 80)"  
  2.   
  3. GO  
  4.   
  5. EXEC sp_updatestats  
  6.   
  7. GO  
Example:
Example
Query 6: Retrieve All dependencies of Stored Procedure:
This query return all objects name that are using into stored procedure like table, user define function, another stored procedure.
Query:
  1. ;WITH stored_procedures AS (  
  2.   
  3. SELECT  
  4.   
  5. oo.name AS table_name,  
  6.   
  7. ROW_NUMBER() OVER(partition by o.name,oo.name ORDER BY o.name,oo.name) AS row  
  8.   
  9. FROM sysdepends d  
  10.   
  11. INNER JOIN sysobjects o ON o.id=d.id  
  12.   
  13. INNER JOIN sysobjects oo ON oo.id=d.depid  
  14.   
  15. WHERE o.xtype = 'P' AND o.name LIKE '%SP_NAme%' )  
  16.   
  17. SELECT Table_name FROM stored_procedures  
  18.   
  19. WHERE row = 1  
Example:
Example
Query 7: Find Byte Size Of All tables in database
  1. SELECT sob.name AS Table_Name,  
  2.   
  3. SUM(sys.length) AS [Size_Table(Bytes)]  
  4.   
  5. FROM sysobjects sob, syscolumns sys  
  6.   
  7. WHERE sob.xtype='u' AND sys.id=sob.id  
  8.   
  9. GROUP BY sob.name  
Example:
Example
Query 8: Get all table that don’t have identity column:
Query:
  1. SELECT  
  2.   
  3. TABLE_NAME FROM INFORMATION_SCHEMA.TABLES  
  4.   
  5. where  
  6.   
  7. Table_NAME NOT IN  
  8.   
  9. (  
  10.   
  11. SELECT DISTINCT c.TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS c  
  12.   
  13. INNER  
  14.   
  15. JOIN sys.identity_columns ic  
  16.   
  17. on  
  18.   
  19. (c.COLUMN_NAME=ic.NAME))  
  20.   
  21. AND  
  22.   
  23. TABLE_TYPE ='BASE TABLE'  
Example:
Example
Query 9: List of Primary Key and Foreign Key for Whole Database
  1. SELECT  
  2.   
  3. DISTINCT  
  4.   
  5. Constraint_Name AS [Constraint],  
  6.   
  7. Table_Schema AS [Schema],  
  8.   
  9. Table_Name AS [TableName] FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE  
  10.   
  11. GO  
Example:
Example
Query 10: List of Primary Key and Foreign Key for a particular table
  1. SELECT  
  2.   
  3. DISTINCT  
  4.   
  5. Constraint_Name AS [Constraint],  
  6.   
  7. Table_Schema AS [Schema],  
  8.   
  9. Table_Name AS [TableName] FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE  
  10.   
  11. WHERE INFORMATION_SCHEMA.KEY_COLUMN_USAGE.TABLE_NAME='Table_Name'  
  12.   
  13. GO  
Example:
Example
Query 11: RESEED Identity of all tables
  1. EXEC sp_MSForEachTable '  
  2.   
  3. IF OBJECTPROPERTY(object_id(''?''), ''TableHasIdentity'') = 1  
  4.   
  5. DBCC CHECKIDENT (''?'', RESEED, 0)  
Example:
Example
Query 12: List of tables with number of records
  1. CREATE TABLE #Tab  
  2.   
  3. (  
  4.   
  5. Table_Name [varchar](max),  
  6.   
  7. Total_Records int  
  8.   
  9. );  
  10.   
  11. EXEC sp_MSForEachTable @command1=' Insert Into #Tab(Table_Name, Total_Records) SELECT ''?'', COUNT(*) FROM ?'  
  12.   
  13. SELECT * FROM #Tab t ORDER BY t.Total_Records DESC;  
  14.   
  15. DROP TABLE #Tab;  
Example:
Example
Query 13: Get the version name of SQL Server
  1. SELECT @@VERSION AS Version_Name  
Example:
Example
Query 14: Get Current Language of SQL Server
  1. SELECT @@LANGUAGE AS Current_Language;  
Example:
Example
Query 15: Disable all constraints of a table
  1. ALTER TABLE Table_Name NOCHECK CONSTRAINT ALL  
Example:
Example
Query16: Disable all constraints of all tables
  1. EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'  
Example:
ExampleQuery 17: Get Current Language Id
  1. SELECT @@LANGID AS 'Language ID'  
Example:
Example
Query18: Get precision level used by decimal and numeric as current set in Server:
  1. SELECT @@MAX_PRECISION AS 'MAX_PRECISION'  
Example:
Example
Query 19: Return Server Name of SQL Server
  1. SELECT @@SERVERNAME AS 'Server_Name'  
Example:
Example
Query 20: Get name of register key under which SQL Server is running
  1. SELECT @@SERVICENAME AS 'Service_Name'  

Example:
Example
Query 21: Get Session Id of current user process
  1. SELECT @@SPID AS 'Session_Id'  
Example:
Example
Query22: Get Current Value of TEXTSIZE option
  1. SELECT @@TEXTSIZE AS 'Text_Size'  
Example:
Example
Query 23: Retrieve Free Space of Hard Disk
  1. EXEC master..xp_fixeddrives  
Example:
example
Query24: Disable a Particular Trigger

Syntax:
  1. ALTER TABLE Table_Name DISABLE TRIGGER Trigger_Name  
Example:
  1. ALTER TABLE Employee DISABLE TRIGGER TR_Insert_Salary  
Query 25: Enable a Particular Trigger
Syntax:
  1. ALTER TABLE Table_Name ENABLE TRIGGER Trigger_Name  
Example:
  1. ALTER TABLE Employee ENABLE TRIGGER TR_Insert_Salary  
Query 26: Disable All Trigger of a table
We can disable and enable all triggers of a table using previous query, but replacing the "ALL" instead of trigger name.
Syntax:
  1. ALTER TABLE Table_Name DISABLE TRIGGER ALL  
Example:
  1. ALTER TABLE Demo DISABLE TRIGGER ALL  
Query 27: Enable All Trigger of a table
  1. ALTER TABLE Table_Name ENABLE TRIGGER ALL  
Example:
  1. ALTER TABLE Demo ENABLE TRIGGER ALL  
Query 28: Disable All Trigger for database
Using sp_msforeachtable system stored procedure we enable and disable all triggers for a database.
Syntax:
  1. Use Database_Name  
  2.   
  3. Exec sp_msforeachtable "ALTER TABLE ? DISABLE TRIGGER all"  
Example:
example
Query29: Enable All Trigger for database
  1. Use Demo  
  2.   
  3. Exec sp_msforeachtable "ALTER TABLE ? ENABLE TRIGGER all"  
Example:
example
Query30: List of Stored procedure modified in last N days
  1. SELECT name,modify_date  
  2.   
  3. FROM sys.objects  
  4.   
  5. WHERE type='P'  
  6.   
  7. AND DATEDIFF(D,modify_date,GETDATE())< N  
Example:
example
Query31: List of Stored procedure created in last N days
  1. SELECT name,sys.objects.create_date  
  2.   
  3. FROM sys.objects  
  4.   
  5. WHERE type='P'  
  6.   
  7. AND DATEDIFF(D,sys.objects.create_date,GETDATE())< N  
Example:
Example
Query32: Recompile a stored procedure
  1. EXEC sp_recompile'Procedure_Name';  
  2.   
  3. GO  
Example:
Example
Query 33: Recompile all stored procedure on a table
  1. EXEC sp_recompile N'Table_Name';  
  2.   
  3. GO  
Example:
Example
Query 34: Get all columns of a specific data type:
Query:
  1. SELECT OBJECT_NAME(c.OBJECT_ID) as Table_Name, c.name as Column_Name  
  2.   
  3. FROM sys.columns AS c  
  4.   
  5. JOIN sys.types AS t ON c.user_type_id=t.user_type_id  
  6.   
  7. WHERE t.name = 'Data_Type'  
Example:
Example
Query 35: Get all Nullable columns of a table
  1. SELECT OBJECT_NAME(c.OBJECT_ID) as Table_Name, c.name as Column_Name  
  2.   
  3. FROM sys.columns AS c  
  4.   
  5. JOIN sys.types AS t ON c.user_type_id=t.user_type_id  
  6.   
  7. WHERE c.is_nullable=0 AND OBJECT_NAME(c.OBJECT_ID)='Table_Name'  
Example:
Example
Query 36: Get All table that don’t have primary key
  1. SELECT name AS Table_Name  
  2.   
  3. FROM sys.tables  
  4.   
  5. WHERE OBJECTPROPERTY(OBJECT_ID,'TableHasPrimaryKey') = 0  
  6.   
  7. ORDER BY Table_Name;  
Example:
Example
Query 37: Get All table that don’t have foreign key
  1. SELECT name AS Table_Name  
  2.   
  3. FROM sys.tables  
  4.   
  5. WHERE OBJECTPROPERTY(OBJECT_ID,'TableHasForeignKey') = 0  
  6.   
  7. ORDER BY Table_Name;  
Example:
Example
Query 38: Get All table that don’t have identity column
  1. SELECT name AS Table_Name  
  2.   
  3. FROM sys.tables  
  4.   
  5. WHERE OBJECTPROPERTY(OBJECT_ID,'TableHasIdentity') = 0  
  6.   
  7. ORDER BY Table_Name;  
Example:
Example
Query 39: Get First Date of Current Month
  1. SELECT CONVERT(VARCHAR(25),DATEADD(DAY,-(DAY(GETDATE()))+1,GETDATE()),105) First_Date_Current_Month;  
Example:
Example
Query 40: Get last date of previous month
  1. SELECT CONVERT(VARCHAR(25),DATEADD(DAY,-(DAY(GETDATE())),GETDATE()),105) Last_Date_Previous_Month;  
Example:
Example
Query 41: Get last date of current month
  1. SELECT CONVERT(VARCHAR(25),DATEADD(DAY,-(DAY(GETDATE())), DATEADD(MONTH,1,GETDATE())),105) Last_Date_Current_Month;  
Example:
Example
Query 42: Get first date of next month
  1. SELECT CONVERT(VARCHAR(25),DATEADD(DAY,-(DAY(GETDATE())), DATEADD(MONTH,1,GETDATE())+1),105) First_Date_Next_Month;  
Example:
Example
Query 43: Swap the values of two columns
  1. UPDATE Table_Name SET Column1=Column2, Column2=Column1  
Example:
Example
Query 44: Remove all stored procedure from database
  1. Declare @Drop_SP Nvarchar(MAX)  
  2.   
  3. Declare My_Cursor Cursor For Select [name] From sys.objects where type = 'p'  
  4.   
  5. Open My_Cursor  
  6.   
  7. Fetch Next From My_Cursor Into @Drop_SP  
  8.   
  9. While @@FETCH_STATUS= 0  
  10.   
  11. Begin  
  12.   
  13. Exec('DROP PROCEDURE ' + @Drop_SP)  
  14.   
  15. Fetch Next From My_Cursor Into @Drop_SP  
  16.   
  17. End  
  18.   
  19. Close My_Cursor  
  20.   
  21. Deallocate My_Cursor  
Example:
Example
Query 45: Remove all views from database
  1. Declare @Drop_View Nvarchar(MAX)  
  2.   
  3. Declare My_Cursor Cursor For Select [name] From sys.objects where type = 'v'  
  4.   
  5. Open My_Cursor  
  6.   
  7. Fetch Next From My_Cursor Into @Drop_View  
  8.   
  9. While @@FETCH_STATUS = 0  
  10.   
  11. Begin  
  12.   
  13. Exec('DROP VIEW ' + @Drop_View)  
  14.   
  15. Fetch Next From My_Cursor Into @Drop_View  
  16.   
  17. End  
  18.   
  19. Close My_Cursor  
  20.   
  21. Deallocate My_Cursor  
Example:
Example
Query 46: Drop all tables
  1. EXEC sys.sp_MSforeachtable @command1 = 'Drop Table ?'  
Example:
Example
Query 47: Get information of tables’ columns
  1. SELECT * FROM INFORMATION_SCHEMA.COLUMNS  
  2.   
  3. WHERE INFORMATION_SCHEMA.COLUMNS.TABLE_NAME=’Table_Name’  
Example:
Example
Query 48: Get all columns contain any constraints
  1. SELECT TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME FROM INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE  
Example:
Example
Query 49: Get all tables that contain a view
  1. SELECT * FROM INFORMATION_SCHEMA.VIEW_TABLE_USAGE  
Example:
Example
Query 50: Get all columns of table that using in views
  1. SELECT * FROM INFORMATION_SCHEMA.VIEW_COLUMN_USAGE  
Example:

Example