sql server alter column

oracle, you can obtain the information by querying the oracle Data dictionary. The advantage of doing so is that it is convenient to view the table structure in the future and you do not need to find it from the database documentation. It is of application significance for team development. /* ===================================================== =========== */ /* Table: EMP */ /* ===================================================== ========= */ Create table EMP ( "EmpID" NUMBER, "EmpName" VAR

Tags: arc requires IDE number Server index execute execution plan log The source of this article: http://www.cnblogs.com/wy123/p/6008477.html For statistics on the number of rows of data estimates, previously written on the non-related columns (separate or separate index columns) of the algorithm, refer to here. 　　Today, let's write the statistical information on the calculation methods and potential problems of the composite index at the time of est

There are a couple of concepts to talk about before you start."Overwrite Query"When an index contains all the columns referenced by a query, it is often referred to as an "overwrite query.""Index Overlay"If the returned data column is contained in the key value of the index, or is contained in the key value of the index + the key value of the clustered index, then Bookup Lookup does not occur, because the index entry is found, and there is no need to

'))Drop function [dbo]. [function name]7 getting user-created object informationSELECT [name],[id],crdate from sysobjects where xtype= ' U '8 determining whether a column existsif exists (SELECT * from syscolumns where id=object_id (' table name ') and name= ' column name ')ALTER TABLE table name drop column name9 Jud

function:SQL code 1. select 1 where 1 = (select isnull (col_name (object_id (admin), 3), meiyoucilie )) The preceding statement indicates that the name of the third column in the admin table is obtained and compared with 1. An error is returned, by reporting the error, we can expose the name of the third column, instead of using the syscolumns table. The col_name function is used. It has two parameters: th

What is a self-increment columnThe ID column can be set to self-increment in SQL Server. That is, you do not need to specify a value for the ID, the column is automatically assigned a value by SQL Server, and the value of each new

Document directory Example Stuff: For xml path References Example Yesterday I encountered an SQL Server problem: I need to write a stored procedure to process data in several tables. The problem is that I want to splice multiple rows in one column of a table into one row, for example, a table has two columns of data: Category Name A

The pivot and Unpivot relational operators are the new features provided by SQL Server 2005, so when you use pivot and UNPIVOT for databases that are upgraded to SQL Server 2005, the compatibility level of the database must be set to 90 (you can use sp_ Dbcmptlevel stored procedures to set the compatibility level. Usi

1, the column to change careersAfter the data is calculated and processed, the data source needed for the front-end chart is generated directly, but the program needs to write the data into the middle table, and query the data directly from the middle table the next time the data is queried.1.1-Column line wrapping syntaxTable_sourceUnpivot (Value_columnFor Pivot_columnIn ()1.2 Row

Tags: --sql Server 2005, or 2012:select * from Information_schema.tables--sql server 2000:select * from sysobjects WHERE xt ype= ' u ' select * from sysobjects WHERE xtype= ' u ' select table_name from GEOVIDNU. Information_schema. Tablesselect sobjects.namefrom sysobjects sobjectswhere sobjects.xtype = ' U ' EXEC sp_

Tags: Allow set article Lin Line system height method DBCCOriginal: SQL Server modifies the Identity column method (Memo)SQL Server modifies the identity column method----allow updates to system tables exec sp_configure ' allow u

Label:Source: When SQL Server creates a composite index, the composite index column order affects the performance of the query Talk about composite indexes Write index blog Too much, has not wanted to write, there are two reasons:One is the suspicion that there are fried leftovers, brothers have said: Index, as long as the query criteria to build the index on the

In daily SQL Server development, identity columns of the Identity type are often used as the auto-increment numbers of a table structure. For exampleArticleNumber, record number, and so on. The reference of the Self-increasing ID column greatly facilitates the databaseProgramDevelopment, but sometimes this stubborn field type also brings some trouble. 1. Modify