how to check blank value in sql server

Query whether a table exists:In practice, you may need to delete a table. before deleting a table, you are advised to check whether the table exists to prevent returning error messages. In SQL Server, you can use the following statement: If object_id (n'table name', n'u') is not null drop table name; note, differences between common tables and temporary tables: I

Implementation principle: to determine whether a registry exists is determined by finding whether the registry contains the corresponding identifier. Note: Windows XP and Windows 7 registry are stored in different ways, 32-bit and 64-bit operating system registry are stored in different ways, you need to determine separately. Only 32-bit operating systems are judged here. Source code: //// Check whether oracle is installedFunction number chec

Label: --enable the operation of other servers in this server execsp_configure'Show advanced Options',1 Reconfigure --Output Message execsp_configure'Ad Hoc Distributed Queries',1 Reconfigure --Output Message --Increase INSERT into OPENROWSET('SQLOLEDB','JX3XXIEDNR3UCIDF';'SA';'Aa12345', Yyg.dbo.T_Tabel_a) ([Name])VALUES('Zhang Hui') --Delete DELETE OPENROWSET('SQLOLEDB','JX3XXIEDNR3UCIDF';'SA';'Aa12345', yyg.dbo.T_Tabel_a)WHERE [Name] = 'Zhang Hu

TABLEdbo. Orders; CREATE TABLEdbo. Orders (OrderIDINT not NULL, EmpidINT not NULL, CustIDVARCHAR(Ten) not NULL, Orderts DATETIME2 not NULL, QtyINT not NULL, CONSTRAINTPk_ordersPRIMARY KEY(OrderID)); /** Add PRIMARY KEY constraint **/ ALTER TABLEDbo. OrdersADD CONSTRAINTFk_orders_employeesFOREIGN KEY(Empid)REFERENCESdbo. Employees (Empid); /** Add default constraint **/ ALTER TABLEDbo. OrdersADD CONSTRAINTDft_orders_ordertsDEFAULT(Sysdatetime ()) forOrderts; /** Delete

I. Definition:The CHECK constraint is used to limit the range of values in a column.If you define a CHECK constraint for a single column, this column only allows specific values.If you define a CHECK constraint for a table, this constraint limits the value in a specific column.As a database, you must write constraints.

You can obtain the desired data table information from the system table sysobjects in the database. The specific SQL statement is as follows: Select name from sysobjects where type = 'U '; Because the system table sysobjects stores all database objects, type indicates the types of various objects, including:U = User tableS = system tableC = check ConstraintsD = default

The patch version check of SQL Server is not as direct as the windows patch version check. If a System Administrator does not know the patch number corresponding to the SQL Server version, it may also encounter some trouble, there

Kanwi.cn Does your SQL Server Run abnormally recently? No, I am not referring to the common database and operating system problems we will certainly encounter. I mean, have you ever experienced slow server response, unstable operations, heavy Network workload, or a sharp rise in server processing or memory utilization?

results are obtained:Here is a record of the previous checkpoint of Step 2, at which time only two records4. Look at the page condition of the table you just createdDBCC IND ('db_test','t',1);Results:We can see that the above page78 is the page that contains the 5 data you just inserted. (Pagetype=1 is DataPage, pagetype=10 is Iam Page)5. Execute an update itself SQL statement, and then look at the transaction log, and the dirty data in memoryUPDATET

statement_end_offsetEND -statement_start_offset)/2)FROM sys.dm_exec_sql_text(sql_handle) ) AS query_textFROM sys.dm_exec_query_stats ORDER BY [avg_cpu_cost] DESC -- The above DMV only displays the total statistics of the currently cached queries-- In order to find the most frequently run query in the workload, You need to execute the following DMV query. SELECT TOP 10 total_worker_time ,plan_handle,execution_count, (SELECT SUBSTRING(text,statement_start_offset/2+1, (CASE WHEN state

--create a linked serverexecsp_addlinkedserver'JX3XXIEDNR3UCIDF',' ','SQLOLEDB','JX3XXIEDNR3UCIDF' execsp_addlinkedsrvlogin'JX3XXIEDNR3UCIDF','false',NULL,'SA','Aa12345' --IncreaseINSERT intoJx3xxiednr3ucid.yyg.dbo.T_Tabel_a ([Name])VALUES('Zhang Hui')--DeleteDELETEJx3xxiednr3ucid.yyg.dbo.T_Tabel_aWHERE [Name] = 'Zhang Hui' --ChangeUPDATEJx3xxiednr3ucid.yyg.dbo.T_Tabel_aSET [Name] = 'Chen Qiu Water' WHEREId= 4--CheckSELECT * fromjx3xxiednr3ucid.yyg.dbo.T_Tabel_a--remove a linked serverex

for SPs, the new version is located in; HKLM \ SOFTWARE \ Microsoft \ MSSQLServer \ CurrentVersion \ CSDVersion .; for SP2, the value is 8.00.534. if the CSDVersion key does not exist,; no SP has been installed. function CheckMinSQLVersion ClearErrors ReadRegStr $0 HKLM "SOFTWARE \ Microsoft \ MSSQLServer \ CurrentVersion" "CurrentVersion" IfErrors SQLServerNotFound SQLServerFound: readRegStr $4 HKLM "SOFTWARE \ Microsoft \ MSSQLServer \ CurrentVersi

Check whether the table exists 1. Use System View: SYS. Tables Select name from SYS. tables where name = 'tablaname' and type = 'U' Type = 'U' is used to exclude stored procedures, views, and system tables. It refers to the user table user_table. 2. Use the System View: sysobjectsSelect * From sysobjects where id = object_id ('usersubsyscenthistory _ null') and xtype = 'U' Xtype = 'U' is used to exclude stored procedures, views, and system tables. It

In SQL, the possible values of logical expressions include true, false, and unknown. They are called three-value logic. The three-value Logic is unique to SQL. Most logical expressions that change to a language have only true or false values. The unknown in SQL usually appea

Use? PLACEHOLDER write MySQL query statement, execute error 1 Com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException:You has an error in your SQL syntax; Check the manual, corresponds to your MySQL server version for the right syntax to use near '?,?,?,?) ' At line 1 2 @ sun.reflect.NativeConstructorAccessorImpl.newInstance0 (Native Method) 3 at Sun.reflect.Na

Label:A few years have not been used MySQL data, today in the use of C # access to the MySQL database is a small episode. Error message: You have a error in your SQL syntax; Check the manual-corresponds to your MySQL server version for the right syntax-use??? Of course, the error message is clearly explained by the syntax error of

Uninstall SQL Server first, and then delete the "Microsoft SQL Server" folder generated during installation. Register Delete all HKEY_CURRENT_USER/software/Microsoft SQL Server and HKEY_LOCAL_MACHINE/software/Microsoft

Connection SQLServer2005 failed with error message:Error type:Microsoft OLE DB Provider for ODBC Drivers (0x80004005)[Microsoft] [ODBC SQL Server Driver] [DBNETLIB] General network error. Please check your network documentation.My connection string is: Driver={sql Server};

, containing the number of rows in the table, not including the number of data entries in the index From Sys.dm_db_partition_stats P INNER JOIN sys.objects o On p.object_id = o.object_id where p.object_id= object_id (' Table name ') GROUP BY O.name --by page or district statistics, have performance impact, accurate --Displays space information for the data and indexes of all tables or views in the current database --Include: logical fragmentation, zone fragmentation (fragmentatio

. The sorting operation and grouping operation assume that the two null values are equal. If a column in the table defines the unique constraint, you cannot insert two rows whose column value is null to the table. The group by clause groups all null values in a group. The order by clause lists all null values. Understanding the unknown logical result and null in different language elements is advantageous, which can avoid future troubles. A lot of de