步骤一:了解ALTER TABLE语句 在开始之前,我们先来了解一下ALTER TABLE语句的语法。ALTERTABLE语句用于修改已存在的表结构。它的基本语法如下: ALTER TABLE table_name ADD COLUMN column_name_1 data_type [constraint], ADD COLUMN column_name_2 data_type [constraint], ... ADD COLUMN column_name_n data_...
CREATE TABLE test1(a,b); As you can see, the SQLite CREATE TABLE syntax is pretty forgiving, and you don't even have to specify the data types of the table columns. This means that you can also add a new column without specifying its type, like this: ALTER TABLE test1 ADD COLUMN ...
1. 初级封装:函数式抽象 defcreate_table(conn, table_name, columns): columns_sql =', '.join([f'{name}{type}'forname, typeincolumns]) sql =f"CREATE TABLE IF NOT EXISTS{table_name}({columns_sql})" conn.execute(sql) # 调用示例 create_table(conn,'users', [ ('id','INTEGER PRIMARY ...
ADD COLUMN语句。SQLite 3.1.3(2005-02-20)增加了对格式2的读写支持。 格式3:增加了对ALTER TABLE…ADD COLUMN语句非空缺省值的支持,从SQLite 3.1.4(2005-03-11)开始支持格式3。 格式4:增加了index声明时对DESC关键字的支持(之前的版本1,2,3都忽略了DESC关键字),此外格式4还增加了对2种boolean记录类型的...
ALLOW_PAGE_LOCKS = ON ) ON ) ON -- 添加维一约束 ALTER TABLE TableDescription ADD CONSTRAINT un_TableDescription_TableName UNIQUE (TableName ) /*** 对象 : Table [dbo].[FieldDescription] ***/ CREATE TABLE [dbo] .[FieldDescription] ( IDENTITY (1 ,1 ) NOT FOR REPLICATION NOT NULL, ...
column += columns[i]+","; } column=column.substring(0, column.length()-1); sql = "INSERT INTO " + from + " (" + column + ") " + " SELECT " + column + " FROM " + to; //4、删除修改之前的数据表 db.execSQL("DROP TABLE IF EXISTS " + to); ...
If your app needs multiple databases, LitePal support it completely. You can create as many databases as you want at runtime. For example: LitePalDBlitePalDB=newLitePalDB("demo2",1);litePalDB.addClassName(Singer.class.getName());litePalDB.addClassName(Album.class.getName());litePalDB...
The following example creates a database called employee.db. This also creates an employee table with 3 columns (id, name and title), and a department table in the company.db database. We’ve purposefully missed the deptid column in the employee table. We’ll see how to add that later....
• Multiple cells/rows/columns selection. • View table data with a convenient filter. • Sort records by tapping on column title. • Edit blob data as hex or show it as preview if possible. Alter Table • View, edit or add table fields, indexes, foreign keys, checks. ...
The following example creates a database called employee.db. This also creates an employee table with 3 columns (id, name and title), and a department table in the company.db database. We’ve purposefully missed the deptid column in the employee table. We’ll see how to add that later....