问题
I am using Spring JdbcTemplate with the DAO pattern to access a database. Instead of creating the database tables manually, I am looking for a way to generate the tables in the DAO layer.
I understand that I can use the JdbcTemplate to execute statements, I am only looking for the right place to do it.
Is there a best practice for that?
回答1:
Slightly offtopic:
Is it absolutely necessary that you need to execute the DDL commands from within your code? In fact I do think it is a good idea to have separation between db admin and db usage. Our Oracle database security setup here is actually set up so that the tables are set up using a different database user (DB_OWNER), than the one running the SELECTs, INSERTs, DELETEs are run by DB_USER.
This prevents accidentially deleting tables or modifying the schema and also allows the DB_USER to be setup such that only the privileges that are absolutely necessary are granted, which adds a layer of security.
I suppose it depends on the nature of your service/application, but think about the benefit of creating the tables inside the code (and whether a possible bug in the DDL code could accidentially destroy production data).
回答2:
You can use the execute(String) method:
public void execute(String sql) throws DataAccessException
Issue a single SQL execute, typically a DDL statement.
Specified by: execute in interface JdbcOperationsParameters: sql - static SQL to execute
Throws: DataAccessException - if there is any problem
However as beny23 mentions I would be suspicious of an actual need to do this programatically in a live application.
回答3:
Use .update() methods available in the (Simple)JdbcOperations, the number they return is the number of affected rows. They're supposed to be specifically used for both INSERT and UPDATE statements.
来源：https://stackoverflow.com/questions/2101439/spring-jdbc-how-to-create-the-tables