sql-delete

问题 I need to do this DELETE FROM konta WHERE taken != '' But != doesn't exist in mysql. Anyone know how to do this? 回答1: DELETE FROM konta WHERE taken <> ''; 回答2: The != operator most certainly does exist! It is an alias for the standard <> operator. Perhaps your fields are not actually empty strings, but instead NULL ? To compare to NULL you can use IS NULL or IS NOT NULL or the null safe equals operator <=>. 回答3: You may be using old version of Mysql but surely you can use DELETE FROM konta

问题 I am trying to delete all voters from a voters table where they are not registered as a democrat or republican AND only voted once. I have a database with three tables, congress_members, voters, and votes and have to JOIN votes with voters in order to delete the right data. This code finds the data I want to delete: SELECT voters.* FROM voters JOIN votes ON voters.id = votes.voter_id WHERE party = 'green' OR party = 'na' OR party = 'independent' GROUP BY votes.voter_id HAVING COUNT(*) = 1;

问题 I am trying to delete all voters from a voters table where they are not registered as a democrat or republican AND only voted once. I have a database with three tables, congress_members, voters, and votes and have to JOIN votes with voters in order to delete the right data. This code finds the data I want to delete: SELECT voters.* FROM voters JOIN votes ON voters.id = votes.voter_id WHERE party = 'green' OR party = 'na' OR party = 'independent' GROUP BY votes.voter_id HAVING COUNT(*) = 1;

问题 I would like to make an app where the user clicks a button, and the SQLite database is cleared. Here's what I've tried so far: db.delete(TABLE_NAME, null, null); What am I doing wrong? 回答1: Your delete() call is correct. Did you get writable database? Here is example of method using delete: /** * Remove all users and groups from database. */ public void removeAll() { // db.delete(String tableName, String whereClause, String[] whereArgs); // If whereClause is null, it will delete all rows.

问题 Hi i want to Send Delete Request to server using Volley along Headers and body parameters. but i am not able to send request successfully What i have tried JSONObject jsonbObjj = new JSONObject(); try { jsonbObjj.put("nombre", Integer.parseInt(no_of_addition .getText().toString())); jsonbObjj.put("cru", crue); jsonbObjj.put("annee", 2010); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } VolleyRequest mVolleyRequest = new VolleyRequest( Method.DELETE, url,

问题 I am having trouble with a simple DELETE statement in SQL with unexpected results , it seems to add the word to the list??. Must be something silly!. but i cannot see it , tried it a few different ways. All the same result so quite confused. public void IncludeWord(string word) { // Add selected word to exclude list SqlConnection conn = new SqlConnection(); String ConnectionString = "Data Source = dev\\SQLEXPRESS ;" + "Initial Catalog=sml;" + "User id=** ;" + "Password =*;" + "Trusted

问题 I am trying to run a SQL query to delete rows with id's 163 to 265 in a table I tried this to delete less number of rows DELETE FROM `table` WHERE id IN (264, 265) But when it comes to delete 100's of rows at a time, Is there any query similar to above method I am also trying to use this kind of query but failed to execute it DELETE FROM `table` WHERE id IN (SELECT * FROM table WHERE id = ) Please tell me the query to do the above action... 回答1: If you need to delete based on a list, you can

问题 I recently found and fixed a bug in a site I was working on that resulted in millions of duplicate rows of data in a table that will be quite large even without them (still in the millions). I can easily find these duplicate rows and can run a single delete query to kill them all. The problem is that trying to delete this many rows in one shot locks up the table for a long time, which I would like to avoid if possible. The only ways I can see to get rid of these rows, without taking down the

问题 How can I structure a mySQL query to delete a row based on the max value. I tried WHERE jobPositonId = max(jobPostionId) but got an error? 回答1: Use: DELETE FROM TABLE t1 JOIN (SELECT MAX(jobPositonId) AS max_id FROM TABLE) t2 WHERE t1.jobPositonId = t2.max_id Mind that all the rows with that jobPositonId value will be removed, if there are duplicates. The stupid part about the 1093 error is that you can get around it by placing a subquery between the self reference: DELETE FROM TABLE WHERE

问题 Is this the correct way to do it? DELETE t1, t2, t3, t4 FROM table1 as t1 INNER JOIN table2 as t2 on t1.id = t2.id INNER JOIN table3 as t3 on t1.id=t3.id INNER JOIN table4 as t4 on t1.id=t4.id WHERE t1.username='%s' AND t1.id='%s' 回答1: Yes, that is correct. It works fine here: CREATE TABLE table1 (id int, username nvarchar(30)); CREATE TABLE table2 (id int); CREATE TABLE table3 (id int); CREATE TABLE table4 (id int); INSERT INTO table1 VALUES (1, 'Foo'),(2, 'Bar'); INSERT INTO table2 VALUES