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plurals

POPolicy query execution
primarykey
Id
5693841
data
AcceptedAnswerId
5693850
AnswerCount
2
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2011-04-17T13:41:37.787
FavoriteCount
0
LastActivityDate
2011-04-17T16:37:04
LastEditDate
2011-04-17T14:17:17.870
LastEditorUserId
711206
OwnerUserId
711206
ParentId
0
PostTypeId
1
Score
0
ViewCount
60
LastEditorDisplayName
text
Body
When I insert a new record in the users table, first check email and nickname were not already added. There is a possibility that another user who registers with the same data simultaneously me false result? To clarify: Connect 1: <pre><code> > SELECT * FROM account WHERE username = 'test'; </code></pre> Empty set (0.00 sec) Connect 2: <pre><code>> SELECT * FROM account WHERE username = 'test'; </code></pre> Empty set (0.00 sec) <pre><code>> INSERT INTO account(username) VALUES ('test'); </code></pre> Query OK, 1 row affected (0.01 sec) Connect 1: <pre><code>> INSERT INTO account(username) VALUES ('test'); </code></pre> Error. Duplicate key What I want to know is if MySQL works this way, by running queries when they come, and best practices to use. I noticed that during a transition, the changes made by other connections are not visible. Why? You can use SELECT ... FOR UPDATE outside the transitions? The massive use of foreign key to ensure data integrity is a recommended practice? edit: Put another way. Ignore the stupid example. I want the next user who registers has an age greater than all those already <pre><code>> SELECT MAX (age) FROM account; </code></pre> [... Check if a user's age is higher ...] <pre><code>> INSERT INTO accounts (age) VALUES ('$ var'); </code></pre> How do I make sure that there is a risk to have two users with the same field camp?
Tags
<php><mysql>
Title
Policy query execution
singulars
PostAcceptedAnswerId
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USFederkun
UserOwnerUserId
1. USFederkun
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
2. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId
1. This table or related slice is empty.

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A row detail

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