sql server isnull in where clause

Server into the N-beginning field type, such as Nvarchar-> varchar. Change the date field that needs to have a second type to datatime type (SQL converts all dates into the smalldatetime type)8,true and 1=1Access uses where true to indicate that the condition is true,SQL Server uses where 1=1 to indicate that the cond

How to import/export Excel files from SQL Server /* ============= Basic method for importing/exporting Excel =================== */ To import data from an Excel file to a SQL database, you can simply use the following statement: /* ===================================================== ======= */ -- Assume that the table to be imported already exists. Insert into

it is to increase I/O.2. Vertical and horizontal partition table, reduce the size of the table (Sp_spaceuse)3. Upgrading hardware4, according to the query criteria, index, optimize the index, optimize access mode, limit the data volume of the result set. Note that the fill factor is appropriate (preferably using the default value of 0). The index should be as small as possible, using a Lie Jian index with a small number of bytes (refer to the creation of the index), do not Jianjian a single ind

Label:SQL Server Database performance optimizationRecent project needs, did a period of time SQL Server performance optimization, encountered some problems, but also accumulated some experience, now summed up, with June share. SQL Server performance optimization involves man

search for separate reports of data rows instead of using the group by clause. In this case, SQL statements using the distinct keyword are more efficient. Use group by when you need to calculate Aggregate functions (sum, Count, Max, etc. In addition, if your query always returns a unique row, do not use the distinct keyword. In this case, the distinct keyword only increases the system overhead. As you ca

How to import/export Excel files from SQL Server /* = ======= */ To import data from an Excel file to a SQL database, you can simply use the following statement: /* ===================================================== ===================================== */-- If the table to be imported already existsInsert into Table select * fromOPENROWSET ('Microsoft. JET. O

Label:Get the most complete data dictionary for SQL Server The following code is executed in Microsoft SQL Server 2013 by SELECTSysobjects.name astable name,--sys.extended_properties. [Value] As table description,Syscolumns.name asfield name,--Properties. [Value] As field description,Systypes.name asfield type, Syscol

''' + course + ''' then score else 0 end) [' + course + ']'From (select distinct course from TB) asSet @ SQL = @ SQL + 'from TB group by name'Exec (@ SQL)-- Create @ SQL dynamically and obtain the following script:Select name as name,Max (Case course when 'China' then score else 0 end) language,Max (Case course when 'm

''' + course + ''' then score else 0 end) [' + course + ']'From (select distinct course from TB) asSet @ SQL = @ SQL + 'from TB group by name'Exec (@ SQL)-- Create @ SQL dynamically and obtain the following script:Select name as name,Max (Case course when 'China' then score else 0 end) language,Max (Case course when 'm

SQL Server data storage structure: A page size of 8K (8060) bytes, 8 pages for a disk area, according to B-Tree storage. The difference between commit and rollback. Rollback: Rollback of all transactions; commit: Commit the current transaction. It is not necessary to write transactions in dynamic SQL, if you want to write on the outside, such as: Begin T

to use decimal. All default values are lost. It mainly belongs to the numeric type and date type. All now (), time (), date () must be changed to getdate (). Change all datediff ('D', time1, time2) to datediff (day, time1, time2) Some types of true/false may not be available and must be changed to 1/0. The remarks type must be cast (column as varchar. The value of cursortype must be changed to 1, that is, when the database is opened, the first numeric parameter must be set to 1. Oth

-- 1. What file does SQL consist? /* Answer: SQL is composed of data files and log files */ -- 2. What are the two types of SQL data files? What are the extensions? How many can there be? /* Answer: SQL data files are divided into primary and secondary data files. There is only one primary data file. The second

data rows instead of using the group by clause. In this case, SQL statements using the distinct keyword are more efficient. Use group by when you need to calculate Aggregate functions (sum, Count, Max, etc. In addition, if your query always returns a unique row, do not use the distinct keyword. In this case, the distinct keyword only increases the system overhead. As you can see, there are a lot of technol

Tags: using strong data Io re cThe following SQL statement takes Northwind as an example1. Do not use functions and expressions on the left side of the "=" in the WHERE clause because the system cannot apply the index in a function or an expressionSELECT * from Customers WHERE Cast (CustomerID as VARCHAR) = ' 1 '--clustered Index scan full table scanSELECT * from Customers WHERE CustomerID = ' 1 '--clustere

is NULL) GODECLARE@colINTSELECT@col =1 DECLARE@SQLNVARCHAR(4000)SET@SQL =' SELECT SomeCol2From TestWHERE 1 =1 ' IF@col is not NULL SET@SQL = @SQL +' and [email protected] ' EXECsp_executesql @SQL, N' @InnerParamcol INT ', @colSET STATISTICSIoOFFGOWe can see that the dynamic

SQL Server Report statistics-parameterized Dynamic Compaction row-to-column, sqlserverregression List all table structures first: -- Title Report -- table real-time Water Fee: hx_t_received -- field Charge Department id: hx_f1_mentid 1. Charge Department name: hx_fdepartmentname water fee information ID: hx_freceivableid -- charge type: hx_ftype (Water Fee (1 ): [Account Opening (table) Water Supply categ

the server to find the keyword to be executed in our disorganized SQL statement. Efficiency, because our sensory nerves are not sensitive to changes below seconds, we temporarily think that the order of SQL statements we write is irrelevant! ", Huh, huh. In fact, the server will have a detailed record of

the day of the year,DW represents the day of the week and returns an integer default of 1 for SundayGETDATE No parametersSelect GETDATE ()Back to 2009-04-28 18:57:24.153Returns the current system date and time.DayDateSelect Day (' 2007-12-11 ') returns 11Returns an Integer that represents the part of the day of the specified date.Equivalent toDATEPART (dd, date)MonthDateSelect month (' 2007-12-11 ') returns 12Returns an Integer that represents the part of the month of the specified date.Equival

Tags: isnull font name ROM null arch weight 2.x arcTable information field information in SQL Server These things are also placed in the system tables, and the following SQL statement is used to query the field information for a table. SelectT1.name Table_name,t2.namecol_name, T3.name+'('+Convert(varchar( $), T2.length

-driven cursor (keyset): You must be aware of the changes to the data to a certain extent, but you do not need to understand all the latest inserts.A. the table must have a unique index.B. Only the key set is in tempdb, not the entire dataset, which has a favorable impact on the performance of the entire server.C. You are aware of the modifications (changes and deletions) made to the rows that are part of the key set. You are not aware of the addition.3) DYNAMIC Cursor (DYNAMIC)A. Completely dyn