Updating a specific row in sql
Dropping or adding triggers on the target table of the update invalidates the update statement. Perhaps you meant "Is it possible to update a specific column in a row without changing the value of the other columns in the same row? Regardless of the number of columns defined for the table, you have complete control over exactly how many values you update.The data I'm going to provide won't be very complete, so I apologize in advance for that, and will happily supplement with more on request.I mostly just don't know where to begin looking, and don't want to just provide a firehose of irrelevant information. There's a minorly large table (half a gig or so, nothing outrageous but not tiny) that, every once in a while, will get into a state where particular update statements will reliably time out with a lock wait error (the timeout config is set to either 20 or 40 seconds, I don't remember offhand).The update statements in question are always of the form where id is an autoincrementing primary key, and the set clause is variable.When the problem occurs (which I'll see in logs at the application level), I can replicate the timeout 100% of the time.I'm kind of at the end of my toolset for diagnosing this, and my Google Fu has not been sufficient. Show processlist was unhelpful--the only non-Sleeping process was the one timing out.EDIT: Here is some seemingly relevant output from show engine innodb status (the query shown here is one that lock timeouts): ---TRANSACTION 1DB65EBE4, ACTIVE 16 sec starting index read mysql tables in use 1, locked 1 LOCK WAIT 2 lock struct(s), heap size 376, 1 row lock(s) My SQL thread id 86652526, OS thread handle 0x7f869e69a700, query id 7651019033 localhost my_cli_user Updating update `footable` set `updated_at`='2016-03-01 ' where `primary_key` = primary_key_of_interest ------- TRX HAS BEEN WAITING 16 SEC FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 0 page no 941788 n bits 80 index `PRIMARY` of table `databasename`.`footable` trx id 1DB65EBE4 lock_mode X locks rec but not gap waiting ---TRANSACTION 1DB6640ED, not started My SQL thread id 86659263, OS thread handle 0x7f86a86e3700, query id 7651064214 some.internal.host2 client_username Waiting for query cache lock SELECT * FROM `footable` WHERE (`footable`.`record_alias` = 'some_idstring') LIMIT 1 ---TRANSACTION 1DB664584, not started My SQL thread id 85428235, OS thread handle 0x7f86b167d700, query id 7651064207 some.internal.host2 client_username Waiting for query cache lock SELECT bar_foo_jointable.some_column, footable.* FROM `footable` INNER JOIN `bar_foo_jointable` ON `footable`.primary_key = `bar_foo_jointable`.foo_primary_key WHERE ((`bar_foo_jointable`.bar_primary_key = some_primary_key_4)) LIMIT 1 when the update is running/waiting. I've greatly pruned the show engine results to keep from spamming the question, so let me know if there's something you think that should be there that isn't.
The positioned update statement depends on the cursor and any tables the cursor references.
In this article I will show you a number of different ways to use the UPDATE statement to modify the data in your SQL Server tables.
There are multiple ways to use the UPDATE statement to update a SQL Server table.
If you want to review the complete syntax of the UPDATE statement then please refer to Books Online.
To properly show you how to use the UPDATE statement I will need to create a few tables to hold some sample data. Below is the code to create my Toy table: In order to show you how to UPDATE a table from data in another table I need to build a second sample data table that I will call New Toy Price.