sql server alter column

Error behavior: Microsoft OLE DB Provider for SQL Server error ' 80040e2f ' cannot insert value NULL into column ' id ', table ' Web.dbo.dingdan '; column does not allow null values. INSERT failed. /untitled-2.asp, line 115 Reason Analysis: SQL database, the ID

In SQL Server, the identity column is often used. This self-increasing field operation is indeed more convenient. But it sometimes brings some trouble. Example 1: when some data is deleted from a table, the number of the auto-increment column is no longer a series of connections. In this case, we can use the following

. Extended_properties. VALUE fromsyscolumnsINNER JOINSYS. Extended_properties onSyscolumns.id=SYS. Extended_properties. major_id andsyscolumns. COLID=SYS. Extended_properties. minor_idINNER JOINSYSOBJECTS onSyscolumns.id=sysobjects.idWHERESysobjects.name=So.name andSyscolumns.name=Sc.name) Description--So . Name Table name, SC. Name Column name fromSYS. COLUMNS Sc,sys. TYPES St,sys. SYSOBJECTS so--Column na

syscolumns SCOn so. ID = SC. IDAnd columnproperty (SC. ID, SC. Name, 'isidentity ') = 1Where upper (so. Name) = upper (@ table_name) Reference: DBCC checkident Check the current Identifier value of the specified table. If necessary, correct the Identifier value. Syntax DBCC checkident('Table_name' [,{Noreseed| {Reseed [, New_reseed_value]}}]) Parameters 'Table_name' Is the name of the table whose current identity value is to be checked. The table name must comply with the i

= SC. idAnd columnproperty (SC. id, SC. name, 'isidentity ') = 1Where upper (so. name) = upper (@ Table_name) Reference: DBCC CHECKIDENT Check the current Identifier value of the specified table. If necessary, correct the Identifier value. Syntax DBCC CHECKIDENT('Table_name'[,{NORESEED| {RESEED [, New_reseed_value]}}]) Parameters 'Table_name' Is the name of the table whose current identity value is to be checked. The table name must comply with the identifier rules. For more information, seeId

intoScore (Stuno, Stuname, Coursename, score)VALUES('2','Jone','Math', -); INSERT intoScore (Stuno, Stuname, Coursename, score)VALUES('2','Jone','中文版', the); INSERT intoScore (Stuno, Stuname, Coursename, score)VALUES('2','Jone','Geography', the); GO SELECT * fromScore;Stuno Stuname Coursename Score1 Tom Math 801 Tom 中文版 821 Tom Geography 842 Jone Math 792 Jone 中文版 882 Jone Geography 86--Changerow to column:SELECT Stuno, Stuname, Math, 中文版, Geography from score MAX scorelist

For SQL SERVER 2000 and earlier versions, you need to use a self-added column, which is implemented in conjunction with temporary tables. Copy Code code as follows: SELECT [Autoid] = IDENTITY (int,1,1), * into #temp_table the from table name; Copy Code code as follows: SELECT * from #temp_table; Starting with

However, Microsoft SQL server has an important defect in processing such indexes, that is, the operations that should have been compiled into index seek are compiled into index scanning, which may cause serious performance degradation. For example, assume that a table T has an index (cityid, sentdate, userid) and now has a paging list function, to query several records greater than a certain multi-

Calculate the column and average value in the SQL Server database Strictly speaking, Having does not need a subtable, but Having without a subtable does not have practical significance. If you only need one table, you can use the Where clause for all purposes. For practice, Having assumes at least two tables and a aggregate function based on the second table. The