You could query the dataset and then loop the selected rows to set them as delete. var rows = dt.Select(“col1 > 5”); foreach (var row in rows) { row.Delete(); } dt.AcceptChanges(); … and you could also create some extension methods to make it easier … myTable.Delete(“col1 > 5”); public static DataTable Delete(this DataTable table, string … Read more
Due to the locking implementation issues, MySQL does not allow referencing the affected table with DELETE or UPDATE. You need to make a JOIN here instead: DELETE gc.* FROM guide_category AS gc LEFT JOIN guide AS g ON g.id_guide = gc.id_guide WHERE g.title IS NULL or just use a NOT IN: DELETE FROM guide_category AS … Read more
Nope, you’d need to run multiple statements. Because you need to delete from two tables, consider creating a temp table of the matching ids: SELECT U.Id INTO #RecordsToDelete FROM Users U JOIN LinkingTable J ON U.Id = J.U_Id … And then delete from each of the tables: DELETE FROM Users WHERE Id IN (SELECT Id … Read more
Basically destroy runs any callbacks on the model while delete doesn’t. From the Rails API: ActiveRecord::Persistence.delete Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can’t be persisted). Returns the frozen instance. The row is simply removed with an SQL DELETE statement on the … Read more
If you delete an item from a collection, that collection has been changed and you can’t continue to enumerate through it. Instead, use a For loop, such as: for(int i = dtPerson.Rows.Count-1; i >= 0; i–) { DataRow dr = dtPerson.Rows[i]; if (dr[“name”] == “Joe”) dr.Delete(); } dtPerson.AcceptChanges(); Note that you are iterating in reverse … Read more
You simply need to specify on which tables to apply the DELETE. Delete only the deadline rows: DELETE `deadline` FROM `deadline` LEFT JOIN `job` …. Delete the deadline and job rows: DELETE `deadline`, `job` FROM `deadline` LEFT JOIN `job` …. Delete only the job rows: DELETE `job` FROM `deadline` LEFT JOIN `job` ….
MySQL doesn’t reduce the size of ibdata1. Ever. Even if you use optimize table to free the space used from deleted records, it will reuse it later. An alternative is to configure the server to use innodb_file_per_table, but this will require a backup, drop database and restore. The positive side is that the .ibd file … Read more
You need the %in% operator. So, df1[!(df1$name %in% df2$name),] should give you what you want. df1$name %in% df2$name tests whether the values in df1$name are in df2$name The ! operator reverses the result.
You can try like this: //—deletes a particular title— public boolean deleteTitle(String name) { return db.delete(DATABASE_TABLE, KEY_NAME + “=” + name, null) > 0; } or public boolean deleteTitle(String name) { return db.delete(DATABASE_TABLE, KEY_NAME + “=?”, new String[]{name}) > 0; }
You can do this with window functions. It will order the dupes by empId, and delete all but the first one. delete x from ( select *, rn=row_number() over (partition by EmployeeName order by empId) from Employee ) x where rn > 1; Run it as a select to see what would be deleted: select … Read more