SQL Server

The primary key is a constraint (constraint), which is attached to an index that can be either a clustered index or a nonclustered index.So there is a primary key on a (or a set) of fields that can only indicate that he has an index on it, but not

------------------------Create an advanced junction-------------------------58. Using Table/Column aliases--58.1. Using aliases on tablesSELECT Cust_name,cust_contactFrom customers as c,orders as o,orderitems as OiWHERE c.cust_id =o.cust_idand

1: Add a field to the tableAlter table [table name] add [column name] Type2: Delete FieldAlter table [table name] Drop column [column name]3: Modify the field type in the table (you can modify the type of the column, whether it is empty)ALTER TABLE [

1. FreeTDS must be installedInstalling the Pdo_dblib extension requires the installation of FreeTDS first.FreeTDS's latest stable version is 0.91, this can be downloaded on the official website http://www.freetds.org/, can also be downloaded in http:

Index categoryUnique index (unique) clustered index (CLUSTERED) nonclustered index (nonclustered)The difference between a primary key and a unique indexA primary key is a constraint, and a unique index is an index, and the two are essentially

Statement and PreparestatementThe Bookphone database has been established in SQL Server, contains the Bookphone table, there are bookphone classes in Eclipse, three string-type values1.import java.sql.Connection;import Java.sql.DriverManager;import

In the full recovery model, SQL Server records all the logs in the log file, so how does SQL Server log the logs?Check the contents of the log file Select* from Sys.fn_dblog (null,null)CURENTLSN: Current log sequence numberOperation: Type of

SQL Server emulated array--sql is less capable of handling strings, such as I want to iterate through strings like 1,2,3,4,5, and if you use arrays, traversal is simple, but T-SQL does not support arrays, so it is cumbersome to deal with them. The

DECLARE @geogGEOGRAPHY;DECLARE @geomGEOMETRY;SET @geom =Geometry::stgeomfromtext ('POLYGON (-99.213546752929688 19.448402404785156,-99.2157974243164 19.449802398681641,-99.2127456665039 19.450002670288086, -99.213546752929688 19.448402404785156))',43

--SELECT INTO table2 from table1--INSERT INTO table2 select table1 explanationCreate Tableuserinformation (IDint Identity(10001,1), UIDint, namenvarchar( -), ageint, Birthdaynvarchar( -), Addressnvarchar( -), Countrynvarchar( -), Provincenvarchar( -)

Https://msdn.microsoft.com/zh-cn/library/ms178600.aspxReturns the line number where the error occurred, causing the run TRY ... Catch block for the catch construct.GrammarError_line ()return valueWhen called in a CATCH block: Returns the

CREATE proc [dbo]. [Sp_getpagedlist](@pageIndex int,@pageSize int,@orderBy nvarchar (512),@columns varchar (512),@tableName varchar (512),@where nvarchar (max))AsBegindeclare @sql nvarchar (max)DECLARE @currPage intSet @[email protected]*

　　　　　operation of the digital data UseMasterGoIF EXISTS(SELECT * fromsysdatabasesWHERENAME='QZone')--determine if the database existsBEGIN --represents the beginning of a statement block (DROP DATABASEQZone--Delete Database First if database

TriggerIntroduction to Triggers: a trigger (trigger) is a special stored procedure that is executed either by the program or not by hand, but by an event, which is activated when a table is manipulated (insert,delete, update) , triggers are often

For MS SQL Server databases, there are several issues that are misleading and, even though many SQL Server DBAs are wrong or not fully aware, I would like to write a few articles that explain these easy-to-understand mistakes in depth, I also hope

One: Execution plan generation processWhen it comes to execution planning, the first thing to know is the process of executing the plan, so that you can do it, and I'll draw a diagram below:1. Analysis ProcessThese three are easier to understand,

A: What happens when select encounters a performance-poor update?1. Use the original person table, insert 6 data, because it is 4000 bytes, so two data is a data page, such as:1 DROP TABLE dbo. Person2 CREATE TABLE person (ID INT identity,name CHAR (

One: What are the locks?Before learning to lock, you must know how many locks there are??? Usually as a code farmer we only need to know the following several locks can ...1.S (Share) lockFor ease of understanding, we can think of it as a shared

How to completely delete the SQL Server Registry: sqlserver Generally, when you uninstall the database, you want to completely delete the registry information. The following describes how to completely delete the SQL Server registry for your

SQL Server multi-Table query optimization solution highlights, sqlserver The multi-Table query optimization solution of SQL Server is what we will introduce in this article. We provide the optimization solution and specific optimization examples,