如何只复制表结构? [英] How to copy only the table structure?

问题描述

我想创建一个数据库.它最多有 9 个表，将来可能会超过.但是表的结构(列数和列名)对于所有表都是相同的.我知道有一个选项可以复制表的结构并重命名并使用它，但我不知道如何准确地做到这一点.请给我相关的答案，以减少我的代码.

I want to create a database. It has up to 9 tables in future it may exceed. But the structure (number of columns and column name) of table is same for all tables. I know that there is an option to copy the structure of table and rename it and use it but I don't know how to do it exactly. Please give me the relevant answer so that it reduces my code.

推荐答案

您可以通过 PRAGMA table_info ()

例如

String sqlstr = " PRAGMA table_info (" + table_name + ")";
        Cursor csr = db.rawQuery(sqlstr, null);

生成的光标具有带列的行:-

The resultant cusors has rows with columns :-

cid(rowid)

name(列名)

type(列类型，例如 INTEGER)

type (column type e.g. INTEGER)

notnull(如果可以为空则为 0)

notnull (0 if can be null)

dflt_value(如果有默认值)

pk(0 如果不是主键的一部分，否则 1,2...如果是主键的一部分)

pk (0 if not part of the primary key otherwise 1,2... if part of the primary key)

然后您可以从中构建 SQL.

You could then build the SQL from this.

另一种选择是通过以下方式提取用于创建表的SQL:-

Another alternative could be to extract the SQL used to create the table via :-

SELECT sql FROM sqlite_master WHERE type='table' AND name='<yourtable>'

然后您可以更改结果 SQL，将基表名称更改为新表名称.

You could then alter the resultant SQL, changing the base table name to the new table name.

第三个选项是使用类似的东西复制表格

A third option is to copy the table using something like

CREATE TABLE newtable AS SELECT * FROM basetable WHERE 0

然而，这不是结构的完整副本，例如未创建主键.

However, this isn't a full comprehensive copy of the structure, e.g. primary keys aren't created.

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