Sqlite 简明教程
SQLite - ALTER TABLE Command
SQLite ALTER TABLE 命令修改现有表而不执行数据的完整转储和重新加载。你可以使用 ALTER TABLE 语句重命名表，并且可以使用 ALTER TABLE 语句在现有表中添加其他列。
SQLite ALTER TABLE command modifies an existing table without performing a full dump and reload of the data. You can rename a table using ALTER TABLE statement and additional columns can be added in an existing table using ALTER TABLE statement.
除重命名表和在现有表中添加列外，SQLite 中 ALTER TABLE 命令不支持任何其他操作。
There is no other operation supported by ALTER TABLE command in SQLite except renaming a table and adding a column in an existing table.
Syntax
下面是 ALTER TABLE 的基本语法，用于重命名现有表。
Following is the basic syntax of ALTER TABLE to RENAME an existing table.
ALTER TABLE database_name.table_name RENAME TO new_table_name;以下是 ALTER TABLE 的基本语法，用于在现有表中添加新列。
Following is the basic syntax of ALTER TABLE to add a new column in an existing table.
ALTER TABLE database_name.table_name ADD COLUMN column_def...;Example
考虑包含如下记录的 COMPANY 表 -
Consider the COMPANY table with the following records −
ID NAME AGE ADDRESS SALARY
---------- ---------- ---------- ---------- ----------
1 Paul 32 California 20000.0
2 Allen 25 Texas 15000.0
3 Teddy 23 Norway 20000.0
4 Mark 25 Rich-Mond 65000.0
5 David 27 Texas 85000.0
6 Kim 22 South-Hall 45000.0
7 James 24 Houston 10000.0现在，让我们尝试使用 ALTER TABLE 语句重命名该表，如下所示 -
Now, let’s try to rename this table using ALTER TABLE statement as follows −
sqlite> ALTER TABLE COMPANY RENAME TO OLD_COMPANY;上述 SQLite 语句将 COMPANY 表重命名为 OLD_COMPANY。现在，让我们尝试在 OLD_COMPANY 表中添加新列，如下所示 -
The above SQLite statement will rename COMPANY table to OLD_COMPANY. Now, let’s try to add a new column in OLD_COMPANY table as follows −
sqlite> ALTER TABLE OLD_COMPANY ADD COLUMN SEX char(1);现在，COMPANY 表已更改，并且以下内容将成为 SELECT 语句的输出。
COMPANY table is now changed and following will be the output from SELECT statement.
ID NAME AGE ADDRESS SALARY SEX
---------- ---------- ---------- ---------- ---------- ---
1 Paul 32 California 20000.0
2 Allen 25 Texas 15000.0
3 Teddy 23 Norway 20000.0
4 Mark 25 Rich-Mond 65000.0
5 David 27 Texas 85000.0
6 Kim 22 South-Hall 45000.0
7 James 24 Houston 10000.0应注意，新添加的列填充为 NULL 值。
It should be noted that newly added column is filled with NULL values.