drop-table

问题 Why does dropping a table in PostgreSQL require ACCESS EXCLUSIVE locks on any referenced tables? How can I reduce this to an ACCESS SHARED lock or no lock at all? i.e. is there a way to drop a relation without locking the referenced table? I can't find any mention of which locks are required in the documentation, but unless I explicitly get locks in the correct order when dropping multiple tables during concurrent operations, I can see deadlocks waiting on an AccessExclusiveLock in the logs,

问题 I created table t1 in Oracle 12c. Table has data and it is partitioned on list partition and also has subpartitions. Now I want to delete whole table and all associated partitions (and subpartitions). Is this the right command to delete all? DROP TABLE t1 PURGE; 回答1: When you run DROP then the table is removed entirely from database, i.e. the table does not exist anymore. If you just want to remove all data from that table run truncate table T1 drop storage; You can also truncate single (sub-

来源： https://stackoverflow.com/questions/59720477/how-to-delete-every-table-in-a-specific-schema-in-postgres

来源： https://stackoverflow.com/questions/59720477/how-to-delete-every-table-in-a-specific-schema-in-postgres

问题 GreenDAO supports DaoMaster.dropAllTables() and DaoMaster.createAllTables(). I'm looking for similar functionality in RoomDB. Does RoomDB supports this functionality ?? The use-case for this functionality is, when the user tries to login with new mobile number to my app, i want to clear the data of old login number by showing a warning dialog message and allow login with new number. 回答1: Room supports dropping and creating tables only during a migration between schema versions. You can gain

问题 I'm developing a new system from an old system. The new system is using mysql and java. I want to start with a reduced number of tables. When I delete a table lets say X, how can I cause all references to X to be deleted as well, so if table Y has a FK to table X then on table Y the FK and the column used in the FK get deleted as well? simplified example: CREATE TABLE `Y` ( `yID` int(11) NOT NULL AUTO_INCREMENT, `yName` varchar(50) NOT NULL, ... ) ENGINE=InnoDB; CREATE TABLE `user` ( `userID`

问题 Sorry for the wall of text guys but this one requires expliaining, way too much code to post... I'm importing fixed width files into access in methods that require data entry. I import the file using transferText into two specs (ones global, the other is special circumstance). I have a function that uses DAO to cycle through all Field objects in TableDefs to build a duplicate table including an AutoIncrement PK so I have the ability to edit these records. I push the data into that table with

问题 I'd like to ask if it is possible to handle dropping table command and break it if some conditions are not met? 回答1: I'm going to guess that you are trying to ask: How do I prevent a DROP TABLE from succeeding based on certain application-defined conditions If so, your only built-in option is to use permissions. See GRANT and REVOKE in the PostgreSQL manual. If you want something more complex, you can write a ProcessUtility_hook , but this requires that you write an extension in C that is

问题 I first drop a table in SQL Server 2008 (after that it shows the message that the command was executed sucessfully). I then tried to create a table with the same name, and it showed me an error. After closing the SSMS window and re opening it it tried to create the table with the same name again and it succeeded. What is going on? 回答1: You can't drop and create the same table in the same batch in sql server see MSDN Their examples use GO to break up the two commands. Semi colon might work,

问题 I first drop a table in SQL Server 2008 (after that it shows the message that the command was executed sucessfully). I then tried to create a table with the same name, and it showed me an error. After closing the SSMS window and re opening it it tried to create the table with the same name again and it succeeded. What is going on? 回答1: You can't drop and create the same table in the same batch in sql server see MSDN Their examples use GO to break up the two commands. Semi colon might work,