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How to remove not null constraint in sql server using query
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ALTER TABLE YourTable ALTER COLUMN YourColumn columnType NULL
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How to add not null constraint to existing column in MySQL
I have table name called "Person" with following column names
2 Answers
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记一次数据库表自增长（Auto Increment）故障 - 数据库(内核) - 清泛网 - ...
...主键值。
我们不妨创建一个测试表说明问题：
CREATE TABLE IF NOT EXISTS `test` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB;
然后插入一行问题数据：
INSERT INTO test (id, name) VALUES (2147483647...
Why is SSE scalar sqrt(x) slower than rsqrt(x) * x?
... there are some info, especially about rsqrt (cpu is using internal lookup table with huge approximation, which makes it much simpler to get the result). It may seem, that rsqrt is so much faster than sqrt, that 1 additional mul operation (which isn't to costly) might not change the situation here. ...
Best way to synchronize local HTML5 DB (WebSQL Storage, SQLite) with a server (2 way sync) [closed]
...ize the lib (at each startup for example).
It will automatically create 2 tables (if they don't already exists, one to store all the new or modified elements (table new_elem) and one to store the date of the last sync (table sync_info). It will also create SQLite triggers in order to watch the INSE...
SQL Server Index Naming Conventions [closed]
...dexes
All of my index name take the form of
<index or key type>_<table name>_<column 1>_<column 2>_<column n>
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Is there a version control system for database structure changes?
...the version (such as removing a column). Each migration is numbered, and a table keeps track of your current db version.
To migrate up, you run a command called "db:migrate" which looks at your version and applies the needed scripts. You can migrate down in a similar way.
The migration scripts the...
What columns generally make good indexes?
...portant role in query optimization and searching the results speedily from tables. So it is most important step to select which columns to be indexed. There are two major places where we can consider indexing: columns referenced in the WHERE clause and columns used in JOIN clauses. In short, such co...
What is the difference between Scope_Identity(), Identity(), @@Identity, and Ident_Current()?
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The ident_current(name) returns the last identity created for a specific table or view in any session.
The identity() function is not used to get an identity, it's used to create an identity in a select...into query.
The session is the database connection. The scope is the current query or the c...
How do I bottom-align grid elements in bootstrap fluid layout
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This is the only acceptable answer! @Lukas's will ignore widths on columns that don't fill a row. And DOM manipulation for styling... SMH.
– Archonic
May 30 '15 at 3:59
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