derby

问题 I have the following schema: TableA Name TableB Name A foreign key from TableB.Name to TableA.Name I insert 2500 records into table B and one record into TableA. I then issue the update statement "update TableB set Name = 'new' where Name = 'old'". I then issue the update statement to change TableA.Name from 'old' to 'new' in the same transaction. I put timing code just around the update statement for TableB and discovered that with the foreign key it taks 9.7 seconds to perform the update

问题 For unit testing is it better to mock the data layer or use an embedded database like derby? I know that it also depends on the purpose of the testing. But if I go with derby I don't have to mock all the objects and I assume that would be easier. On the other hand I understand that that is more towards integration testing. So which one is more common for unit testing? Thanks. Update according to comments: So I have derby configured now but my manager insists on using easymock. We are using

问题 I am trying to start an application on Glassfish 4 server but it gives me some strange exception: Internal Exception: java.sql.SQLException: Error in allocating a connection. Cause: Connection could not be allocated because: java.net.ConnectException : Error connecting to server localhost on port 1527 with message Connection refused: connect. Could it be because I don't have SQL? I am not sure how to fix it. 回答1: You need to start the Derby Network Server, and have it listen on port 1527 on

问题 I installed easysoft odbc derby driver in windows 7 and try to connect to derby database after I configure on ODBC Data Source Administrator DSN and connection succeed. then i tried on php script //commz is the DSN name ind ODBC data source admin $connection = odbc_connect("commz",$user, $password); if ($result = odbc_exec($connection, "SELECT * FROM ADDRESSBOOK")) print "Command executed successfully<BR><BR>"; else print "Error while executing command<BR><BR>"; // Print results while(odbc

问题 How can I truncate a VARCHAR to the table field length AUTOMATICALLY in Derby using SQL? To be specific: CREATE TABLE A ( B VARCHAR(2) ); INSERT INTO A B VALUES ('1234'); would throw a SQLException: A truncation error was encountered trying to shrink VARCHAR '123' to length 2. Is there a easy way to suppress this exception? 回答1: No. You should chop it off after checking the meta-data. Or if you don't wanna check the meta-data everytime, then you must keep both your code and database in sync.

问题 How can I truncate a VARCHAR to the table field length AUTOMATICALLY in Derby using SQL? To be specific: CREATE TABLE A ( B VARCHAR(2) ); INSERT INTO A B VALUES ('1234'); would throw a SQLException: A truncation error was encountered trying to shrink VARCHAR '123' to length 2. Is there a easy way to suppress this exception? 回答1: No. You should chop it off after checking the meta-data. Or if you don't wanna check the meta-data everytime, then you must keep both your code and database in sync.

问题 I have a sql question on derby database: Select a.name, a.starttime, a.endtime From a How can I add to the above sql statement such that I can get the difference in hours between the start time and end time? (I only know that for mysql there is a DATEDIFF function, but I am not sure about what function should I use for derby db) Thanks. 回答1: In Derby there is a TIMESTAMPDIFF: for instance: select {fn timestampdiff(SQL_TSI_FRAC_SECOND, startdate, enddate)} as diff 来源： https://stackoverflow.com

问题 I'm using hibernate to persist an entity to my database. For the moment it's a derby DB, but I will be moving it over to an oracle DB soon. in my classname.hbm.xml I have the id defined as such: <id name="id" type="long"> <column name="ID"/> <generator class="increment"/> </id> How do I set the starting value for the id? I'd like it to start at something like 10000 rather than 1. 回答1: I don't think you can, it appears that IncrementGenerator works based off the highest primary key so unless

问题 I'm using hibernate to persist an entity to my database. For the moment it's a derby DB, but I will be moving it over to an oracle DB soon. in my classname.hbm.xml I have the id defined as such: <id name="id" type="long"> <column name="ID"/> <generator class="increment"/> </id> How do I set the starting value for the id? I'd like it to start at something like 10000 rather than 1. 回答1: I don't think you can, it appears that IncrementGenerator works based off the highest primary key so unless