I have created tables in MySQL Workbench as shown below : ORDRE table: PRODUKT table: and ORDRELINJE table: so when I try to insert values into ORDRELINJE table i get: Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails (srdjank.Ordrelinje, CONSTRAINT Ordrelinje_fk FOREIGN KEY (Ordre) REFERENCES Ordre (OrdreID)) I’ve … Read more
There’s a very interesting discussion of this type of issue here: http://www.titov.net/2005/09/21/do-not-use-order-by-rand-or-how-to-get-random-rows-from-table/ I think with absolutely no assumptions about the table that your O(n lg n) solution is the best. Though actually with a good optimizer or a slightly different technique the query you list may be a bit better, O(m*n) where m is the number … Read more
One easy trick that can help with most deadlocks is sorting the operations in a specific order. You get a deadlock when two transactions are trying to lock two locks at opposite orders, ie: connection 1: locks key(1), locks key(2); connection 2: locks key(2), locks key(1); If both run at the same time, connection 1 … Read more
As you are creating a database from scratch, you could use: Here is an identical scenario.
for some reason, the ODBC user is the default username under windows even if you didn’t create that user at setup time. simply typing without specifying a username will attempt to connect with the non-existent ODBC username, and give: Error 1045 (28000): Access denied for user ‘ODBC’@’localhost’ (using password: NO) Instead, try specifying a username … Read more
You can actually do this one of two ways: MySQL update join syntax: ANSI SQL syntax: Pick whichever one seems most natural to you.
Assuming you mean that you are trying to use the source command in order to execute SQL statements from a text file, the error number given appears to be passed through from the POSIX layer. Therefore, using this resource, we can deduce that the error value of 2 means “no such file or directory”. In short, you got the path … Read more
A simple solution would be doing something like this:
Since the suggestion of a loop implies the request for a procedure type solution. Here is mine. Any query which works on any single record taken from a table can be wrapped in a procedure to make it run through each row of a table like so: First delete any existing procedure with the same … Read more
You are using a transaction; autocommit does not disable transactions, it just makes them automatically commit at the end of the statement. What is happening is, some other thread is holding a record lock on some record (you’re updating every record in the table!) for too long, and your thread is being timed out. You … Read more