I was trying to add a primary key to existing table but could not. "alter table custsales add constraint pk_custsales primary key (id,type)" Is this supported? Is there a different syntax to do this? Using ALTER TABLE to add a constraint or a new column marked as PRIMARY KEY is not...
[sqlite] How do I add primary key on existing table? Mohd Radzi Ibrahim Re: [sqlite] How do I add primary key on existing ... Dan Re: [sqlite] How do I add primary key on exist... Mohd Radzi Ibrahim [sqlite] Re: How do I add primary key on e... Igor Tandetnik Reply via ...
AddPrimaryKey ✔(重新构建) AddUniqueConstraint ✔(重新构建) AlterColumn ✔(重新构建) CreateIndex ✔ CreateTable ✔ DropCheckConstraint ✔(重新构建) DropColumn ✔(重新构建) DropForeignKey ✔(重新构建) DropIndex ✔ DropPrimaryKey ✔(重新构建) DropTable ✔ DropUniqueConstraint ✔(...
A table should have only one primary key, but multiple columns can be defined in a single primary key, when multiple columns are being used as a single primary key, then it is called a composite primary key. How many ways to add a primary key to any table in SQLite There are two way...
[Table("user")]publicclassUser{// PrimaryKey is typically numeric[PrimaryKey, AutoIncrement, Column("_id")]publicintId {get;set; } [MaxLength(250), Unique]publicstringUsername {get;set; } ... } 定義C# 類別之後,請呼叫SQLiteConnection類別上的CreateTable泛型方法,以在資料庫中產生資料表。 將...
SQLite supports a limited subset of ALTER TABLE. The ALTER TABLE command in SQLite allows the user to rename a table or to add a new column to an existing table. It is not possible to rename a column, remove a column, or add or remove constraints from a table. ...
`PRIMARY KEY` 定义主键。`FOREIGN KEY` 建立外键约束。 `UNIQUE` 确保字段值唯一。`NOT NULL` 防止字段为空。可以创建索引提高查询效率。`CREATE INDEX` 语句创建索引。索引过多会影响插入和更新性能。使用 `DROP TABLE` 删除表。`DROP INDEX` 可删除索引。事务能保证数据一致性。用 `BEGIN TRANSACTION` 开启...
在SQLite中,创建表格需使用SQL的Data Definition Language(DDL)语句——CREATE TABLE。表格由列名、数据类型和约束条件构成,例如,我们可以创建一个学生信息表格: CREATE TABLE Students ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, age INTEGER, gender CHAR(1), major TEXT ); 这里定义了一个名为Students的...
CREATETABLE[Departments] ( [DepartmentId]INTEGERNOTNULLPRIMARYKEY, [DepartmentName] NVARCHAR(50)NULL);INSERTINTODepartmentsVALUES(1,'IT');INSERTINTODepartmentsVALUES(2,'Physics');INSERTINTODepartmentsVALUES(3,'Arts');INSERTINTODepartmentsVALUES(4,'Math');CREATETABLE[Students] ( ...
});//no primary key db.Fastest<Order>().BulkUpdate(GetList(), new string[]{"id"}, new string[]{"name","time"})//Set the updated column //DataTable db.Fastest<System.Data.DataTable>().AS("Order").BulkUpdate(dataTable,"Id"...