Updating a specific row in sql

26-Mar-2019 19:22 by 10 Comments

Updating a specific row in sql - Yahooanswer best free xxx mobile cam

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.

If columns were specified in the FOR UPDATE clause of the SELECT statement used to generate the cursor, only those columns can be updated.

However, if I craft another statement to do something trivial (like update a completely unrelated column to the value it already has), and that statement executes, then the problem will resolve itself, and the time to execute the original statement will go from timeout to milliseconds (so it's not that the query takes slightly less time, it is many orders of magnitude faster).

A simple query that produces this behavior, which makes me think that this isn't some sort of index behavior (not that I can really rule it out).

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 DEFAULT literal is the only value which you can directly assign to a generated column.

Whenever you alter the value of a column referenced by the -- All the employees except the manager of -- department (WORKDEPT) 'E21' have been temporarily reassigned.

A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared positioned update invalidates the prepared positioned update statement.

Dropping an alias invalidates a prepared update statement if the latter statement uses the alias.

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.

In this article I will show you the most common methods of using the UPDATE statement.