declare @TableName nvarchar(250)--游标中取出的数据表名declare @TableID INT--游标中取出的数据表编号declare @IdentityColum
--SQL批量添加主键脚本
--操作提示:运行此脚本前请记得备份您要操作的数据库
--实现功能:执行脚本后数据库中的所有数据表都会有一个主键
--添加规则1:主键名称为ID(可自己修改),数据类型为整形自增一
--添加规则2:如果数据表已有主键,则不添加
--添加规则3:如果数据表没主键但已存在自增一的标识列,则设置该标识列为主键
--添加规则4:如果数据表没主键且已存在ID列,则会删除掉该列,记得要检查该ID列是否包含重要数据,如果有的话,请执行脚本前改名。
--脚本代码开始
declare @ColumnName nvarchar(250)
set @ColumnName='ID' --要新增的主键列名,可自己修改
declare @TableName nvarchar(250)--游标中取出的数据表名
declare @TableID INT--游标中取出的数据表编号
declare @IdentityColumnName nvarchar(250)--数据表的已有标识列名称
--声明读取数据库所有数据表名和编号的游标
declare mycursor1 cursor for select name,id from dbo.SysObjects WHERE OBJECTPROPERTY(ID, 'ISUSErTable') = 1 order by name
--打开游标
open mycursor1
--从游标里取出数据赋值到我们刚才声明的数据表名变量和数据表编号变量中
fetch next from mycursor1 into @TableName,@TableID
--如果游标执行成功
while (@@fetch_status=0)
begin
--判断当前数据表是否存在主键,如果数据表已有主键则不添加
IF NOT EXISTS (select * from information_schema.key_column_usage where TABLE_NAME=''+@TableName+'')
begin
--如果数据表中已经存在标识列,则将标识列设置为主键
if Exists(Select top 1 1 from sysobjects Where objectproperty(id, 'TableHasIdentity') = 1 and upper(name) = upper(@TableName))
begin
Select @IdentityColumnName=name from syscolumns Where id = @TableID and columnproperty(id, name, 'IsIdentity') = 1
print '当前数据表['+@TableName+']没有主键但有标识列['+@IdentityColumnName+']'
exec ('ALTER TABLE ['+@TableName+'] ADD CONSTRAINT PK_'+@TableName+' PRIMARY KEY CLUSTERED ('+@IdentityColumnName+') ON [PRIMARY]')
print '成功设置数据表['+@TableName+']已有标识列['+@IdentityColumnName+']为主键'
end
else
begin
print '当前数据表['+@TableName+']没有主键和标识列'
IF EXISTS (select * from syscolumns Where ID=OBJECT_ID(N'['+@TableName+']') and+@ColumnName+'')
begin
--如果已有ID列设置有索引,则删除数据表@TableName中指定字段@ColumnName对应的所有约束
declare @ConstraintName varchar (250)--定义当前查询的约束变量
--声明读取数据表中指定字段对应的所有约束列表游标
declare mycursor2 cursor for select name from sysobjects left join sysconstraints on sysconstraints.constid=sysobjects.id where parent_obj=OBJECT_ID(''+@TableName+'') and colid=(select colid from syscolumns where id=OBJECT_ID(''+@TableName+'') and OBJECTPROPERTY(id, N'IsUserTable') = 1 and upper(name)=upper(@ColumnName))
--打开游标
open mycursor2
--从游标里取出数据赋值到约束名称变量中
fetch next from mycursor2 into @ConstraintName
--如果游标执行成功
while (@@fetch_status=0)
begin
--删除当前找到的约束
exec ('ALTER TABLE ['+@TableName+'] DROP CONSTRAINT ['+@ConstraintName+']')
print '已成功删除数据表['+@TableName+']字段['+@ColumnName+']对应的约束['+@ConstraintName+']'
--用游标去取下一条记录
fetch next from mycursor2 into @ConstraintName
end
--关闭游标
close mycursor2
--撤销游标
deallocate mycursor2
--如果存在列[ID]则先删除该列
exec ('ALTER TABLE ['+@TableName+'] DROP COLUMN '+@ColumnName+'')
--添加数据表的主键列ID
exec ('ALTER TABLE ['+@TableName+'] ADD '+@ColumnName+' [int] IDENTITY(1,1) NOT NULL PRIMARY KEY')
end
else
begin
--如果存在列[ID]则直接添加主键列ID
exec ('ALTER TABLE ['+@TableName+'] ADD '+@ColumnName+' [int] IDENTITY(1,1) NOT NULL PRIMARY KEY')
end
print '成功设置数据表['+@TableName+']列['+@ColumnName+']为主键'
end
end
else
begin
print '当前数据表['+@TableName+']已有主键'
end
--用游标去取下一条记录
fetch next from mycursor1 into @TableName,@TableID
end
--关闭游标
close mycursor1
--撤销游标
deallocate mycursor1
--脚本代码结束

MySQLviewshavelimitations:1)Theydon'tsupportallSQLoperations,restrictingdatamanipulationthroughviewswithjoinsorsubqueries.2)Theycanimpactperformance,especiallywithcomplexqueriesorlargedatasets.3)Viewsdon'tstoredata,potentiallyleadingtooutdatedinforma

ProperusermanagementinMySQLiscrucialforenhancingsecurityandensuringefficientdatabaseoperation.1)UseCREATEUSERtoaddusers,specifyingconnectionsourcewith@'localhost'or@'%'.2)GrantspecificprivilegeswithGRANT,usingleastprivilegeprincipletominimizerisks.3)

MySQLdoesn'timposeahardlimitontriggers,butpracticalfactorsdeterminetheireffectiveuse:1)Serverconfigurationimpactstriggermanagement;2)Complextriggersincreasesystemload;3)Largertablesslowtriggerperformance;4)Highconcurrencycancausetriggercontention;5)M

Yes,it'ssafetostoreBLOBdatainMySQL,butconsiderthesefactors:1)StorageSpace:BLOBscanconsumesignificantspace,potentiallyincreasingcostsandslowingperformance.2)Performance:LargerrowsizesduetoBLOBsmayslowdownqueries.3)BackupandRecovery:Theseprocessescanbe

Adding MySQL users through the PHP web interface can use MySQLi extensions. The steps are as follows: 1. Connect to the MySQL database and use the MySQLi extension. 2. Create a user, use the CREATEUSER statement, and use the PASSWORD() function to encrypt the password. 3. Prevent SQL injection and use the mysqli_real_escape_string() function to process user input. 4. Assign permissions to new users and use the GRANT statement.

MySQL'sBLOBissuitableforstoringbinarydatawithinarelationaldatabase,whileNoSQLoptionslikeMongoDB,Redis,andCassandraofferflexible,scalablesolutionsforunstructureddata.BLOBissimplerbutcanslowdownperformancewithlargedata;NoSQLprovidesbetterscalabilityand

ToaddauserinMySQL,use:CREATEUSER'username'@'host'IDENTIFIEDBY'password';Here'showtodoitsecurely:1)Choosethehostcarefullytocontrolaccess.2)SetresourcelimitswithoptionslikeMAX_QUERIES_PER_HOUR.3)Usestrong,uniquepasswords.4)EnforceSSL/TLSconnectionswith

ToavoidcommonmistakeswithstringdatatypesinMySQL,understandstringtypenuances,choosetherighttype,andmanageencodingandcollationsettingseffectively.1)UseCHARforfixed-lengthstrings,VARCHARforvariable-length,andTEXT/BLOBforlargerdata.2)Setcorrectcharacters


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

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

SublimeText3 Linux new version
SublimeText3 Linux latest version

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

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