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How do I add a foreign key to an existing SQLite table?
I have the following table:
9 Answers
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Use cases for NoSQL [closed]
...an using a relational database,
where we have to make joins with different tables to get all the data we need
Besides, this use case is optimal because avoids all the principal limits of a NoSQL database:
Lack of transactions: The application doesn't perform writes but only reads, so we don't ne...
List columns with indexes in PostgreSQL
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Create some test data...
create table test (a int, b int, c int, constraint pk_test primary key(a, b));
create table test2 (a int, b int, c int, constraint uk_test2 unique (b, c));
create table test3 (a int, b int, c int, constraint uk_test3b unique (b), co...
How to create relationships in MySQL
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If the tables are innodb you can create it like this:
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT(...
What do Clustered and Non clustered index actually mean?
... all the columns. You do not have to go first to the index and then to the table.
Writing to a table with a clustered index can be slower, if there is a need to rearrange the data.
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CSS way to horizontally align table
I want to show a table of fixed width at the center of browser window. Now I use
10 Answers
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Table fixed header and scrollable body
I am trying to make a table with fixed header and a scrollable content using the bootstrap 3 table.
Unfortunately the solutions I have found does not work with bootstrap or mess up the style.
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What is the difference between “text” and new String(“text”)?
...al is needed, use of this constructor is unnecessary since strings are immutable.
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Strings are objects in Java, so why don’t we use ‘new’ to create them?
What referential distinction means
Examine the follow...
ALTER TABLE without locking the table?
When doing an ALTER TABLE statement in MySQL, the whole table is read-locked (allowing concurrent reads, but prohibiting concurrent writes) for the duration of the statement. If it's a big table, INSERT or UPDATE statements could be blocked for a looooong time. Is there a way to do a "hot alter", li...
Database design for audit logging
... an idea of what the old record looked like.
So for example, if you had a table called Opportunities to track sales deals, you would actually create two separate tables:
Opportunities
Opportunities_Content (or something like that)
The Opportunities table would have information you'd use to unique...