In some cases, I've had to do a mysqldump to produce a .sql file. After making some changes to the MySQL database for testing and development I want to restore it to the way it was before. So I import the .sql file. In the past I have delete the db and re-created it, and then did te import. Is that necessary? Does import from a .sql file overwrite and totally re-create the database and it's tables, or does it append to it? Thanks!
在某些情况下，我不得不做一个mysqldump来生成一个.sql文件。在对MySQL数据库进行一些更改以进行测试和开发之后，我想将其恢复到以前的状态。所以我导入.sql文件。在过去，我删除了数据库并重新创建了它，然后进行了导入。这有必要吗？从.sql文件导入是否会覆盖并完全重新创建数据库及其表，还是附加到它？谢谢！
2 个解决方案
#1
15
It depends on what commands the SQL file contains. Commands of interest are:
它取决于SQL文件包含的命令。感兴趣的命令是：
DROP DATABASE xxx; # will delete the whole database
DROP TABLE xxx; # unconditionally deletes a table
CREATE TABLE [IF NOT EXISTS] # if IF NOT EXISTS adds the table, does nothing if exists
# otherwise, it adds the table, gives an error if it exists
#2
18
Appends to it, unless the import file specifically treats tables differently.
附加到它，除非导入文件专门以不同方式处理表。
#1
15
It depends on what commands the SQL file contains. Commands of interest are:
它取决于SQL文件包含的命令。感兴趣的命令是：
DROP DATABASE xxx; # will delete the whole database
DROP TABLE xxx; # unconditionally deletes a table
CREATE TABLE [IF NOT EXISTS] # if IF NOT EXISTS adds the table, does nothing if exists
# otherwise, it adds the table, gives an error if it exists
#2
18
Appends to it, unless the import file specifically treats tables differently.
附加到它，除非导入文件专门以不同方式处理表。