sql-delete

I'm trying to delete rows from a table but I get an error. DELETE FROM `chat_messages` ORDER BY `timestamp` DESC LIMIT 20, 50; I get this error at 50: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' 50' at line 1 No idea what's wrong. You cannot specify offset in DELETE 's LIMIT clause. So the only way to do that is to rewrite your query to something like: DELETE FROM `chat_messages` WHERE id IN (select id from (select id FROM `chat_messages` ORDER BY `timestamp` DESC LIMIT 20, 50) x) Supposing that you

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' 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 (1),(2); INSERT INTO table3 VALUES (1),(2); INSERT INTO table4 VALUES (1),(2); SELECT COUNT(*) FROM table1; 2

I have a table in SQL Server. I would like to delete the top 1000 rows from it. However, I tried this, but I instead of just deleting the top 1000 rows it deleted all the rows in the table. Here is the code: delete from [mytab] select top 1000 a1,a2,a3 from [mytab] Martin Smith The code you tried is in fact two statements. A DELETE followed by a SELECT . You don't define TOP as ordered by what. For a specific ordering criteria deleting from a CTE or similar table expression is the most efficient way. ;WITH CTE AS ( SELECT TOP 1000 * FROM [mytab] ORDER BY a1 ) DELETE FROM CTE May be better for

Let's say we have table Sales with 30 columns and 500,000 rows. I would like to delete 400,000 in the table (those where "toDelete='1'" ). But I have a few constraints : the table is read / written "often" and I would not like a long "delete" to take a long time and lock the table for too long I need to skip the transaction log (like with a TRUNCATE ) but while doing a "DELETE ... WHERE..." (I need to put a condition), but haven't found any way to do this... Any advice would be welcome to transform a DELETE FROM Sales WHERE toDelete='1' to something more partitioned & possibly transaction log

Say I have a simple table that has the following fields: ID: int, autoincremental (identity), primary key Name: varchar(50), unique, has unique index Tag: int I never use the ID field for lookup, because my application is always based on working with the Name field. I need to change the Tag value from time to time. I'm using the following trivial SQL code: UPDATE Table SET Tag = XX WHERE Name = YY; I wondered if anyone knows whether the above is always faster than: DELETE FROM Table WHERE Name = YY; INSERT INTO Table (Name, Tag) VALUES (YY, XX); Again - I know that in the second example the ID