ADDPRIMARYKEY(ID); To allow naming of aPRIMARY KEYconstraint, and for defining aPRIMARY KEYconstraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: ALTERTABLEPersons ADDCONSTRAINTPK_PersonPRIMARYKEY(ID,LastName); ...
2.添加字段:ALTER TABLE 表名 ADD 字段名 数据类型[属性]; 3.修改字段:ALTER TABLE 表名 CHANGE 原字段名 新字段名 数据类型[属性]; 4.删除字段:ALTER TABLE 表名 DROP 字段名; 2.添加主键 1.语法:ALTER TABLE 表名 ADD CONSTRAINT 主键名 PRIMARY KEY 表名(主键字段); 3.添加外键 1.语法:ALTER TABL...
MySQL支持多个语句一次执行,因此只需要将alter table ... drop primary key和add constraint ... primary key ...合成一条语句, bisal@mysqldb: [test]> alter table t_primary_key drop primary key, add constraint pk_t_01 primary key (id, ...
SQL复制 ALTERTABLESales.TempSalesReasonADDCONSTRAINTFK_TempSales_SalesReasonFOREIGNKEY(TempID)REFERENCESSales.SalesReason (SalesReasonID)ONDELETECASCADEONUPDATECASCADE; 反馈 此页面是否有帮助? 是否 提供产品反馈| 在Microsoft Q&A 获取帮助
为 的主键约束 AddPrimaryKeyOperation生成SQL 片段。 C# 复制 protected virtual void PrimaryKeyConstraint (Microsoft.EntityFrameworkCore.Migrations.Operations.AddPrimaryKeyOperation operation, Microsoft.EntityFrameworkCore.Metadata.IModel? model, Microsoft.EntityFrameworkCore.Migrations.MigrationComman...
To add a primary key, use the following syntax. ALTER TABLE Customer ADD CONSTRAINT PK_Customer PRIMARY KEY CLUSTERED (Id)Try it live A composite key with multiple columns can also be added to a table. ALTER TABLE Customer ADD CONSTRAINT PK_Customer PRIMARY KEY CLUSTERED (FirstName, LastNam...
When FILESTREAM is specified for a column, the table must also have a column of theuniqueidentifierdata type that has the ROWGUIDCOL attribute. This column must not allow null values and must have either a UNIQUE or PRIMARY KEY single-column constraint. TheGUIDvalue for the column is supplied...
UNIQUE and PRIMARY KEY constraints are always enforced. When importing into a character column that is defined with a NOT NULL constraint, BULK INSERT inserts a blank string when there's no value in the text file. At some point, you must examine the constraints on the whole table. If the...
Query OK, 3 rows affected (0.01 sec) Records: 3 Duplicates: 0 Warnings: 0 1. 2. 3. 2.表查询相关操作 2.1运算符 根据条件搜索结果where > -- 查找年龄大于30 select * from info where age>30; -- 查找id大于1 select * from info where id>1; ...
The below error is generated when attempting to run the first query to create table. General error: 3750 Unable to create or change a table without a primary key, when the system variable 'sql_require_primary_key' is set. Add a primary key to the table or unset this variable to avoid ...