对于PowerDesigner中设计表自动生成Sql的分析
if exists (select 1 from sysobjects where id = object_id('DWLX') and type = 'U') drop table DWLXgo/*==============================================================*//* Table: DWLX *//*========================================================
if exists (select 1 from sysobjects where id = object_id('DWLX') and type = 'U') drop table DWLX go /*==============================================================*/ /* Table: DWLX */ /*==============================================================*/ create table DWLX ( DWLX_NM varchar(36) not null, DWLX_LXBH varchar(6) not null, DWLX_LXMC varchar(64) not null, DWLX_LEVEL int not null, DWLX_FJNM varchar(36) not null, DWLX_MX char(1) not null, constraint PK_DWLX primary key nonclustered (DWLX_NM) ) go
分析constraint PK_DWLX primary key nonclustered (DWLX_NM)这句话:
对表DWLX建立主键约束,主键约束的名字是:PK_DWLX ,主键列是:DWLX_NM。
PRIMARY KEY 约束默认为 CLUSTERED;UNIQUE 约束默认为 NONCLUSTERED。此处指明该表为nonclustered索引(即非聚集索引)。
小注:
1、Sql Server判断某个表是否存在:点击打开链接。
2、SQL Server中clustered与nonclustered的区别 :点击打开链接。
3、GO的意思是本语句块结束的意思,一遇到GO就直接提交到存储引擎。
GO (Transact-SQL)官方文档:点击打开链接

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics



HQL and SQL are compared in the Hibernate framework: HQL (1. Object-oriented syntax, 2. Database-independent queries, 3. Type safety), while SQL directly operates the database (1. Database-independent standards, 2. Complex executable queries and data manipulation).

"Usage of Division Operation in OracleSQL" In OracleSQL, division operation is one of the common mathematical operations. During data query and processing, division operations can help us calculate the ratio between fields or derive the logical relationship between specific values. This article will introduce the usage of division operation in OracleSQL and provide specific code examples. 1. Two ways of division operations in OracleSQL In OracleSQL, division operations can be performed in two different ways.

Oracle and DB2 are two commonly used relational database management systems, each of which has its own unique SQL syntax and characteristics. This article will compare and differ between the SQL syntax of Oracle and DB2, and provide specific code examples. Database connection In Oracle, use the following statement to connect to the database: CONNECTusername/password@database. In DB2, the statement to connect to the database is as follows: CONNECTTOdataba

Interpretation of MyBatis dynamic SQL tags: Detailed explanation of Set tag usage MyBatis is an excellent persistence layer framework. It provides a wealth of dynamic SQL tags and can flexibly construct database operation statements. Among them, the Set tag is used to generate the SET clause in the UPDATE statement, which is very commonly used in update operations. This article will explain in detail the usage of the Set tag in MyBatis and demonstrate its functionality through specific code examples. What is Set tag Set tag is used in MyBati

What is Identity in SQL? Specific code examples are needed. In SQL, Identity is a special data type used to generate auto-incrementing numbers. It is often used to uniquely identify each row of data in a table. The Identity column is often used in conjunction with the primary key column to ensure that each record has a unique identifier. This article will detail how to use Identity and some practical code examples. The basic way to use Identity is to use Identit when creating a table.

Solution: 1. Check whether the logged-in user has sufficient permissions to access or operate the database, and ensure that the user has the correct permissions; 2. Check whether the account of the SQL Server service has permission to access the specified file or folder, and ensure that the account Have sufficient permissions to read and write the file or folder; 3. Check whether the specified database file has been opened or locked by other processes, try to close or release the file, and rerun the query; 4. Try as administrator Run Management Studio as etc.

How to use SQL statements for data aggregation and statistics in MySQL? Data aggregation and statistics are very important steps when performing data analysis and statistics. As a powerful relational database management system, MySQL provides a wealth of aggregation and statistical functions, which can easily perform data aggregation and statistical operations. This article will introduce the method of using SQL statements to perform data aggregation and statistics in MySQL, and provide specific code examples. 1. Use the COUNT function for counting. The COUNT function is the most commonly used

Database technology competition: What are the differences between Oracle and SQL? In the database field, Oracle and SQL Server are two highly respected relational database management systems. Although they both belong to the category of relational databases, there are many differences between them. In this article, we will delve into the differences between Oracle and SQL Server, as well as their features and advantages in practical applications. First of all, there are differences in syntax between Oracle and SQL Server.
